Supplementary Table 1. Primers used in this study.

# Primer name Sequence

1 HglEA KO 5’ Fw ACTAGTGGATCCCCCGTGTAACAGC

2 HglEA KO 5’ Rv GAATTCCTGCAGCCCGGGATTAGCAGACATAGGACA

3 HglEA KO 3’ Fw TCGACCTCGAGGGGGAACGTCCCACGCC

4 HglEA KO 3’ Rv GCGAATTGGGTACCGAAGCAGGACGAAC

5 HglE2 KO 5’ Fw ACTAGTGGATCCCCCGATCAAAAACGTACC

6 HglE2 KO 5’ Rv GAATTCCTGCAGCCCGGGTGTATCCATGTTCCTTTTGTC

7 HglE2 KO 3’ Fw TACCGTCGACCTCGAAGAACTGGCGGAAAAG

8 HglE2 KO 3’ Rv CGGGCCCCCCCTCGACCTTTTGTGGTATAGCC

9 all1643 KO 5’ Fw ACTAGTGGATCCCCCTTATCAGGAGGGGA

10 all1643 KO 5’ Rv GAATTCCTGCAGCCCACCATGAACGCTATG

11 all1643 KO 3’ Fw TACCGTCGACCTCGAGCCTTGGGAGTCGAA

12 all1643 KO 3’ Rv CGGGCCCCCCCTCGAAGGCATAAGGGCCAG

13 hglE2 Fw ATGTCTGCTAATCCCATGGATACACAACAAAAGACCC

14 hglE2 Rv GAATTCCTGCAGCCCGAGGATTCGGAGCCA

15 PpsbA Fw CCTCGAGGGGGGGCCGATCTCAATGAATATTGGTTGAC

16 PpsbA Rv GTGTATCCATGCGAAACGATCCTCA

17 DGD2 Fw TTCGCATGGATACACAACAAAAGACC

18 DGD2 Rv ATTGGGTACCGGGCCGTAAAGCTCGCAC

19 rnpB-RTFw CCAGTTCCGCTATCAGAGAG

20 rnpB-RTRv GAGGAGAGAGTTGGTGGTAAG

21 HglE2 seq Fw1 GCCCAGAAACAATCAAGC

22 HglE2 seq Rv1 GTGTCGGGGTATATTCTTC

23 spec-mid-Fw GCGAGGGCTTTACTAAGCTG

24 hglE-RTFw CCGTAGTCAACCAAGTTG

25 hglE-RTRv TATACTGACTGGCTGCCA

26 Km dw GGGATCTCATGCTGGAG

27 all1643 mid AACCCCATTATCGCCTC

0.1 Out group (PfaA, Shewanella sp. BR-2) type I polyketide synthase [Scytonema millei] Outgroup (PfaA) hypothetical protein QH73_010865 [Scytonema millei VB511283] SDR family NAD(P)-dependent oxidoreductase [Leptolyngbya sp. IPPAS B-1204] acyltransferase domain-containing protein [Leptolyngbya sp. IPPAS B-1204] type I polyketide synthase [[Leptolyngbya] sp. JSC-1] acyltransferase domain-containing protein [Calothrix sp. NIES-3974] MULTISPECIES: acyltransferase domain-containing protein [unclassified Calothrix] acyltransferase domain-containing protein [Calothrix desertica] type I polyketide synthase [Calothrix sp. PCC 7103] acyltransferase domain-containing protein [Calothrix sp. HK-06] polyketide synthase phosphopantetheine-binding HglE [Calothrix sp. NIES-4101] acyltransferase domain-containing protein [Calothrix elsteri] acyltransferase domain-containing protein [Calothrix parietina] polyketide synthase [Nostoc sp. MBR 210] acyltransferase domain-containing protein [Nostoc cycadae] acyltransferase domain-containing protein [Anabaenopsis circularis] beta-ketoacyl synthase [Nostoc sp. HK-01] acyltransferase domain-containing protein [Nostoc sp. PCC 7107] heterocyst glycolipid synthase [Nostoc sp. PCC 7120] acyltransferase domain-containing protein [Trichormus variabilis] type I polyketide synthase [Nostoc sp. PCC 7120] acyltransferase domain-containing protein [Trichormus variabilis] acyltransferase domain-containing protein [Nostoc sp. NIES-2111] acyltransferase domain-containing protein [Nostoc sp. NIES-3756] acyltransferase domain-containing protein [Anabaena sp. 4-3] acyltransferase domain-containing protein [Anabaena sp. CA = ATCC 33047] acyltransferase domain-containing protein [Nostoc sp. PCC 7524] acyltransferase domain-containing protein [Nostoc sp. CENA543] acyltransferase domain-containing protein [Nodularia sp. (in: )] acyltransferase domain-containing protein [Nodularia spumigena] heterocyst glycolipid synthase [Nodularia spumigena CCY9414] acyltransferase domain-containing protein [Nodularia spumigena] acyltransferase domain-containing protein [Nodularia spumigena] polyketide synthase [Nostoc minutum NIES-26] acyltransferase domain-containing protein [Nostoc sp. NIES-4103] acyltransferase domain-containing protein [Calothrix brevissima] acyltransferase domain-containing protein [Calothrix sp. NIES-2098] putative acyl carrier protein [Tolypothrix sp. PCC 7601] acyltransferase domain-containing protein [Microchaete diplosiphon] MULTISPECIES: acyltransferase domain-containing protein [] acyltransferase domain-containing protein [Nostoc sp. RF31YmG] acyltransferase domain-containing protein [Nostoc sp. 106C] acyltransferase domain-containing protein [Nostoc sp. T09] acyltransferase domain-containing protein [Calothrix sp. NIES-2100] acyltransferase domain-containing protein [Fortiea contorta] acyltransferase domain-containing protein [Calothrix sp. PCC 7507] polyketide-type polyunsaturated fatty acid synthase PfaA [Cylindrospermum sp. NIES-4074] acyltransferase domain-containing protein [Cylindrospermum stagnale] acyltransferase domain-containing protein [Anabaena sp. PCC 7108] polyketide-type polyunsaturated fatty acid synthase PfaA [Anabaena cylindrica PCC 7122] acyltransferase domain-containing protein [Anabaena cylindrica] polyketide-type polyunsaturated fatty acid synthase PfaA [Anabaena cylindrica PCC 7122] acyltransferase domain-containing protein [Anabaena cylindrica] acyltransferase domain-containing protein [Trichormus variabilis] hypothetical protein DSM107003_24070 [Trichormus variabilis SAG 1403-4b] acyltransferase domain-containing protein [Trichormus sp. NMC-1] acyltransferase domain-containing protein [Trichormus azollae] acyltransferase domain-containing protein [Nostocales cyanobacterium] acyltransferase domain-containing protein [Sphaerospermopsis reniformis] polyketide-type polyunsaturated fatty acid synthase PfaA [Sphaerospermopsis reniformis] polyketide-type polyunsaturated fatty acid synthase PfaA [Sphaerospermopsis kisseleviana NIES-73] acyltransferase domain-containing protein [Sphaerospermopsis kisseleviana] acyltransferase domain-containing protein [Cylindrospermopsis raciborskii] acyltransferase domain-containing protein [Cylindrospermopsis raciborskii] acyltransferase domain-containing protein [Cylindrospermopsis raciborskii] acyltransferase domain-containing protein [Cylindrospermopsis raciborskii] acyltransferase domain-containing protein [Cylindrospermopsis raciborskii] acyltransferase domain-containing protein [Cylindrospermopsis raciborskii] acyltransferase domain-containing protein [Cylindrospermopsis sp. CR12] acyltransferase domain-containing protein [Cylindrospermopsis raciborskii] acyltransferase domain-containing protein [Cylindrospermopsis raciborskii] acyltransferase domain-containing protein [Nostocales cyanobacterium] acyltransferase domain-containing protein [Nostocales cyanobacterium] acyltransferase domain-containing protein [Dolichospermum sp. UHCC 0315A] acyltransferase domain-containing protein [Anabaena sp. 90] Sub-tree containing HglE polyketide synthase [Anabaena sp. AL09] A polyketide synthase [Anabaena sp. LE011-02] polyketide synthase [Anabaena sp. MDT14b] acyltransferase domain-containing protein [Dolichospermum compactum] acyltransferase domain-containing protein [Anabaena sp. WA102] polyketide synthase [Anabaena sp. AL93] acyltransferase domain-containing protein [Aphanizomenon flos-aquae] polyketide synthase [Anabaena sp. WA113] polyketide synthase [Aphanizomenon flos-aquae WA102] polyketide synthase [Aphanizomenon flos-aquae LD13] TPA: polyketide synthase [Anabaena sp. UBA12330] polyketide synthase [Aphanizomenon flos-aquae MDT14a] acyltransferase domain-containing protein [Dolichospermum planctonicum] acyltransferase domain-containing protein [Dolichospermum circinale] acyltransferase domain-containing protein [Dolichospermum circinale] polyketide synthase [Anabaena sp. CRKS33] acyltransferase domain-containing protein [Nostoc sphaeroides] acyltransferase domain-containing protein [Nostoc sp. 'Peltigera membranacea cyanobiont' 232] polyketide synthase [Nostoc punctiforme NIES-2108] acyltransferase domain-containing protein [Nostoc sp. ATCC 53789] acyltransferase domain-containing protein [Nostoc sp. 'Peltigera membranacea cyanobiont' 210A] acyltransferase domain-containing protein [Nostoc sp. KVJ20] acyltransferase domain-containing protein [Nostoc punctiforme] polyketide synthase phosphopantetheine-binding HglE [Nostoc punctiforme PCC 73102] acyltransferase domain-containing protein [Nostoc sp. 'Peltigera membranacea cyanobiont' N6] HglE [Nostoc sp. 'Peltigera membranacea cyanobiont'] acyltransferase domain-containing protein [Nostoc sp. 'Peltigera membranacea cyanobiont' 213] acyltransferase domain-containing protein [Nostoc sp. 'Lobaria pulmonaria (5183) cyanobiont'] acyltransferase domain-containing protein [Nostoc flagelliforme] Acyl carrier protein [Nostoc flagelliforme CCNUN1] acyltransferase domain-containing protein [Nostoc commune] acyltransferase domain-containing protein [Nostoc calcicola] acyltransferase domain-containing protein [Nostoc linckia] acyltransferase domain-containing protein [Nostoc linckia] polyketide synthase [Hassallia byssoidea VB512170] acyltransferase domain-containing protein [[Scytonema hofmanni] UTEX B 1581] acyltransferase domain-containing protein [Tolypothrix sp. NIES-4075] type I polyketide synthase [Scytonema hofmannii] acyltransferase domain-containing protein [Tolypothrix campylonemoides] acyltransferase domain-containing protein [Scytonema sp. HK-05] acyltransferase domain-containing protein [Scytonema sp. NIES-4073] type I polyketide synthase [Mastigocladopsis repens] acyltransferase domain-containing protein [Scytonema tolypothrichoides] polyketide synthase [ thermalis WC527] acyltransferase domain-containing protein [Fischerella muscicola] acyltransferase domain-containing protein [Mastigocladus laminosus] acyltransferase domain-containing protein [Mastigocladus laminosus] acyltransferase domain-containing protein [Westiellopsis prolifica] acyltransferase domain-containing protein [Fischerella sp. PCC 9339] acyltransferase domain-containing protein [Fischerella sp. PCC 9431] acyltransferase domain-containing protein [Hapalosiphon sp. MRB220] acyltransferase domain-containing protein [Fischerella sp. NIES-4106] acyltransferase domain-containing protein [Fischerella thermalis] acyltransferase domain-containing protein [Fischerella thermalis] acyltransferase domain-containing protein [Fischerella sp. NIES-3754] acyltransferase domain-containing protein [Fischerella major] acyltransferase domain-containing protein [Fischerella thermalis] acyltransferase domain-containing protein [Fischerella thermalis] acyltransferase domain-containing protein [Fischerella thermalis] polyketide synthase [Fischerella thermalis CCMEE 5196] acyltransferase domain-containing protein [Fischerella thermalis] acyltransferase domain-containing protein [Fischerella thermalis] acyltransferase domain-containing protein [Fischerella thermalis] acyltransferase domain-containing protein [Fischerella thermalis] acyltransferase domain-containing protein [Fischerella thermalis] acyltransferase domain-containing protein [Fischerella sp. PCC 9605] acyltransferase domain-containing protein [cyanobacterium PCC 7702] acyltransferase domain-containing protein [Chlorogloeopsis fritschii] acyltransferase domain-containing protein [Rivularia sp. PCC 7116] polyketide-type polyunsaturated fatty acid synthase PfaA [Rivularia sp. PCC 7116] acyltransferase domain-containing protein [Calothrix parasitica] acyltransferase domain-containing protein [Mastigocoleus testarum] heterocyst glycolipid synthase [Richelia intracellularis HH01] TPA: polyketide synthase [ bacterium UBA8553] acyltransferase domain-containing protein [Chroococcales cyanobacterium IPPAS B-1203] acyltransferase domain-containing protein [Gloeocapsa sp. PCC 7428] acyltransferase domain-containing protein [Chroogloeocystis siderophila] type I polyketide synthase [Chlorogloeopsis fritschii] beta-ketoacyl synthase [ cyanobacterium JJU2] type I polyketide synthase [Fischerella sp. PCC 9339] type I polyketide synthase [Mastigocladus laminosus] SDR family NAD(P)-dependent oxidoreductase [Westiellopsis prolifica] type I polyketide synthase [Fischerella muscicola] type I polyketide synthase [Fischerella sp. PCC 9431] type I polyketide synthase [Hapalosiphon sp. MRB220] type I polyketide synthase [Fischerella sp. NIES-4106] type I polyketide synthase [Fischerella thermalis] type I polyketide synthase [Fischerella thermalis] acyltransferase domain-containing protein [Fischerella thermalis] type I polyketide synthase [Fischerella major] type I polyketide synthase [Fischerella sp. NIES-3754] type I polyketide synthase [Fischerella thermalis] type I polyketide synthase [Fischerella thermalis] type I polyketide synthase [Fischerella thermalis] SDR family NAD(P)-dependent oxidoreductase [Fischerella thermalis] type I polyketide synthase [Fischerella thermalis] type I polyketide synthase [Fischerella thermalis] type I polyketide synthase [Fischerella thermalis] type I polyketide synthase [Fischerella thermalis] type I polyketide synthase [Fischerella thermalis] type I polyketide synthase [Fischerella thermalis] acyltransferase domain-containing protein [Fischerella thermalis] type I polyketide synthase [Fischerella muscicola] beta-ketoacyl synthase [Fischerella thermalis CCMEE 5319] type I polyketide synthase [cyanobacterium PCC 7702] type I polyketide synthase [Chlorogloeopsis fritschii PCC 6912] acyltransferase domain-containing protein [Chlorogloeopsis fritschii] polyketide-type polyunsaturated fatty acid synthase PfaA [Cylindrospermum sp. NIES-4074] type I polyketide synthase [Trichormus variabilis SAG 1403-4b] type I polyketide synthase [Trichormus sp. NMC-1] type I polyketide synthase [Anabaena sp. PCC 7108] type I polyketide synthase [Trichormus azollae] type I polyketide synthase [Cylindrospermopsis raciborskii] type I polyketide synthase [Cylindrospermopsis raciborskii] type I polyketide synthase [Cylindrospermopsis raciborskii] type I polyketide synthase [Raphidiopsis brookii] type I polyketide synthase [Cylindrospermopsis raciborskii] SDR family NAD(P)-dependent oxidoreductase [Cylindrospermopsis raciborskii] SDR family NAD(P)-dependent oxidoreductase [Cylindrospermopsis raciborskii] type I polyketide synthase [Cylindrospermopsis sp. CR12] type I polyketide synthase [Cylindrospermopsis raciborskii] type I polyketide synthase [Cylindrospermopsis raciborskii] type I polyketide synthase [Cylindrospermopsis raciborskii] type I polyketide synthase [Raphidiopsis curvata] type I polyketide synthase [Sphaerospermopsis kisseleviana] acyltransferase domain-containing protein [Sphaerospermopsis reniformis] type I polyketide synthase [Anabaena cylindrica] type I polyketide synthase [Cuspidothrix issatschenkoi] beta-ketoacyl synthase [Aphanizomenon flos-aquae LD13] beta-ketoacyl synthase [Aphanizomenon flos-aquae MDT14a] beta-ketoacyl synthase [Aphanizomenon flos-aquae WA102] beta-ketoacyl synthase [Anabaena sp. WA113] beta-ketoacyl synthase [Anabaena sp. MDT14b] beta-ketoacyl synthase [Anabaena sp. AL09] Phenolphthiocerol synthesis polyketide synthase type I Pks15/1 [Dolichospermum sp. UHCC 0315A] SDR family NAD(P)-dependent oxidoreductase [Dolichospermum sp. UHCC 0315A] beta-ketoacyl synthase [Anabaena sp. LE011-02] modular polyketide synthase [Anabaena sp. 90] type I polyketide synthase [Anabaena sp. 90] type I polyketide synthase [Aphanizomenon flos-aquae] type I polyketide synthase [Anabaena sp. WA102] beta-ketoacyl synthase [Anabaena sp. AL93] polyketide-type polyunsaturated fatty acid synthase PfaA [Dolichospermum compactum NIES-806] type I polyketide synthase [Dolichospermum compactum] polyketide-type polyunsaturated fatty acid synthase PfaA [Dolichospermum planctonicum] SDR family NAD(P)-dependent oxidoreductase [Dolichospermum planctonicum] type I polyketide synthase [Dolichospermum circinale] type I polyketide synthase [Dolichospermum circinale] beta-ketoacyl synthase [Anabaena sp. CRKS33] type I polyketide synthase [Cylindrospermum stagnale] polyketide-type polyunsaturated fatty acid synthase PfaA [Cylindrospermum stagnale PCC 7417] type I polyketide synthase [Nodularia sp. NIES-3585] type I polyketide synthase [Nodularia spumigena] type I polyketide synthase [Nodularia spumigena] type I polyketide synthase [Nodularia spumigena] acyltransferase domain-containing protein [Nodularia sp. (in: Bacteria)] type I polyketide synthase [Nostoc calcicola] beta-ketoacyl synthase [Nostoc sp. ATCC 43529] SDR family NAD(P)-dependent oxidoreductase [Nostoc sp. PA-18-2419] type I polyketide synthase [Nostoc linckia] type I polyketide synthase [Nostoc linckia] SDR family NAD(P)-dependent oxidoreductase [Nostoc sp. ATCC 53789] type I polyketide synthase [Nostoc punctiforme] type I polyketide synthase [Nostoc sp. KVJ20] acyltransferase domain-containing protein [Nostoc sp. PCC 7524] type I polyketide synthase [Nostoc sp. NIES-4103] heterocyst glycolipid synthase [Nostoc commune HK-02] acyltransferase domain-containing protein [Nostoc commune] Acyl carrier protein [Nostoc flagelliforme CCNUN1] acyltransferase domain-containing protein [Nostoc flagelliforme] acyltransferase domain-containing protein [Scytonema hofmannii] acyltransferase domain-containing protein [Microcystis aeruginosa] acyltransferase domain-containing protein [Microcystis aeruginosa Ma_QC_C_20070823_S13] acyltransferase domain-containing protein [Microcystis aeruginosa TA09] acyltransferase domain-containing protein [Microcystis aeruginosa] acyltransferase domain-containing protein [Microcystis aeruginosa] acyltransferase domain-containing protein [Microcystis aeruginosa] acyltransferase domain-containing protein [Microcystis panniformis] acyltransferase domain-containing protein [Microcystis aeruginosa] acyltransferase domain-containing protein [Microcystis aeruginosa Ma_SC_T_19800800_S464] acyltransferase domain-containing protein [Chroococcales cyanobacterium metabat2.561] acyltransferase domain-containing protein [Microcystis aeruginosa] acyltransferase domain-containing protein [Microcystis aeruginosa] Sub-tree containing HglE2 acyltransferase domain-containing protein [Microcystis aeruginosa] acyltransferase domain-containing protein [Microcystis aeruginosa] acyltransferase domain-containing protein [Microcystis sp. MC19] acyltransferase domain-containing protein [Microcystis sp. T1-4] acyltransferase domain-containing protein [Microcystis aeruginosa] acyltransferase domain-containing protein [Cyanothece sp. BG0011] acyltransferase domain-containing protein [Trichormus variabilis] acyltransferase domain-containing protein [Nostoc sp. PCC 7120] MULTISPECIES: acyltransferase domain-containing protein [Nostocaceae] polyketide synthase [Moorea producens JHB] acyltransferase domain-containing protein [Moorea producens] acyltransferase domain-containing protein [Nostoc sp. PCC 7524] acyltransferase domain-containing protein [Calothrix sp. PCC 7103] hypothetical protein EBE85_07625 [Hormoscilla sp. GUM007] type I polyketide synthase [Gloeobacter violaceus] type I polyketide synthase [Gloeobacter violaceus] Supplementary Figure 1. Phylogenetic analysis of HglEA and HglE2. PfaA sequence of Shewanella sp. BR-2 was used as a query (and outgroup) of BLAST search against cyanobacterial sequences. HglEA and HglE2 sequences are highlighted by orange. Two sequences of HglEA are NCBI sequence ID BAB77050.1 (upper one, used in this study) and RUR88086.1 (N663D amino acid change). Black letters indicate the species of heterocystous, and gray letters indicate non-heterocystous cyanobacteria. Blue letters indicate sequences of unclassified species.