7844 Corrections: Proc. Natl. Acad. Sci. USA 78 (1981) Correction. In the article "X-ray diffraction of strained muscle Correction. In the article "Purified lexA protein is a repressor fibers in rigor" by G. R. S. Naylor and R. J. Podolsky, which of the recA and lexA genes" by John W. Little, David W. appeared in the September 1981 issue ofProc. NatL Acad. Sci. Mount, and Celeste R. Yanisch-Perron, which appeared in the USA (78, 5559-5563), two printer's errors occurred. In the July 1981 issue of Proc. NatL Acad. Sci. USA (78, 4199-4203), Abstract, line 5 should read: printer's errors deleted some lines of text. On p. 4202, the last sentence of the first full paragraph should read "A given pro- "the intensity ratio, I(1O/1(11). Because the intensity ratio de- moter gives rise to a run-offtranscript ofa particular size, which pends .. " forms a band in the autoradiogram." On p. 4203, the last sen- tence before the acknowledgements should read "We conclude Also, on p. 5563, in the last paragraph of the Discussion, the that this model, originally based largely on genetic evidence, first-word in line 3 should be "and." is also completely consistent with the known biochemical prop- erties of the lexA and recA proteins. " Correction: In the article "N-(6-Aminohexyl)-5-chloro-1-naph- thalenesulfonamide, a calmodulin antagonist, inhibits cell pro- liferation" by Hiroyoshi Hidaka, Yasuharu Sasaki, Toshio Tan- Correction. In the article "Impaired induction and self-catab- aka, Toyoshi Endo, Shinichi Ohno, Yasuhisa Fujii, and Tetsuji olite repression of extracellular pectate lyase in Erwinia chry- Nagata, which appeared in the July 1981 issue of Proc. Nati santhemi mutants deficient in oligogalacturonide lyase" by Alan Acad. Sci. USA (78, 4354-4357), an undetected printer's error Collmer and Durward F. Bateman, which appeared in the June resulted in the omission of Table 1. The table is reproduced 1981 issue of Proc. Nati Acad. Sci. USA (78, 3920-3924), an here. editorial error and an undetected printer's error occurred in Table 2 on p. 3922. The heading for the first column of data should be (GalUA)2 (the saturated digalacturonic acid). The Table 1. Affinity (IC50) of W-7 and W-5 for calmodulin heading for the third column of data should-be u(GalUA)2 (the W-7 W-5 unsaturated digalacturonic acid). Inhibition of phosphodiesterase activity 28 240 Inhibition of myosin light chain kinase activity 51 230 Displacement of [3H]W-7 from calmodulin 31 210 The IC50 value is defined as the concentration of drug required to produce 50% inhibition of enzyme activity or of labeled W-7 binding to purified calmodulin. These values were determined graphically and all experiments were run in triplicate. Correction. In the article "Tumor-promoting phorbol-esters stimulate myelopoiesis and suppress erythropoiesis in cultures ofmouse bone marrow cells" by Fritz Sieber, Robert K. Stuart, and Jerry L. Spivak, which appeared in the July 1981 issue of Proc. NatL Acad. Sci. USA (78, 4402-4406), several printer's errors occurred in Table 2 on p. 4405. The corrected version ofTable 2 is printed here. Table 2. Colony formation by mixed cultures of TPA-treated and untreated marrow cells TPA treatment Colonies* No. of cells juM min BFU-E CFU-E CFU-GM 1 x 105 None - 53.0 ± 3.9 507 ± 36 15.3 ± 2.7 1 x 105 10 45 0 99± 9 74.7 ± 2.2 1 x 105 1 45 3.5 ± 0.5 ND ND 1 x 105 0.1 45 52.3 ± 2.1 ND ND 5 x 0 104 None 4 0 305 ± 18 100.3 ± 4.8 (Expected) (26.5) (303) (45) 5 x 104 None1 10.8 ± 1.7 ND ND (Expected) (28.3) 5 x 104 None - 51.8 ± 2.9 ND ND with5 x 104 0.1 45 (Expected) (52.7) B6D2F1 marrow cells were incubated in TPA as outlined in Table!1, washed, and cultured either sep- arately or mixed with untreated cells. ND, not done. * Mean of quadruplicate cultures ± SEM. Downloaded by guest on September 25, 2021 Proc. Natl. Acad. Sci. USA Vol. 78, No. 6, pp. 3920-3924, June 1981 Microbiology Impaired induction and self-catabolite repression of extracellular pectate lyase in Erwinia chrysanthemi mutants deficient in oligogalacturonide lyase (phytopathogenic bacteria/exoenzyme regulation/regulatory mutants/product induction/deoxyketuronic acid) ALAN COLLMER* AND DURWARD F. BATEMANt Department of Plant Pathology, Cornell University, Ithaca, New York 14853 Communicated by Ellis B. Cowling, March 4, 1981 ABSTRACT The pectate lyase (PL; EC 4.2.2.2) secreted by Bacteria secrete a variety of pectic enzymes differing in re- the plant pathogenErwinia chrysanthemi is induced and catabolite action mechanism (hydrolysis vs. /3 elimination) and action pat- repressed by different concentrations ofits own product, digalac- tern (exo vs. endo) (7). Regulatory studies thus far have focused turonic acid 4,5-unsaturated at the nonreducing end [u(GalUA)2]. on PL, which cleaves internal linkages in D-galacturonan by (3 Both activities ofu(GalUA)2 depend on its cleavage by oligogalac- elimination, generating a series of oligomers with a 4,5-unsat- turonide Iyase (OGL; EC 4.2.2.6). This intracellular enzyme con- urated bond at the nonreducing end. Several features of PL verts u(GalUA)2 to the deoxyketuronic acid 4-deoxy-L-threo-5-hex- regulation in E. carotovora have recently been described. In- osulose uronic acid, which is then isomerized to 3-deoxy-D-glycero- duction on D-galacturonan is mediated by PL reaction products 2,5-hexodiulosonic acid. An OGL-deficient mutant unable to grow (presumably generated by a basal level of PL): the adaptive lag on u(GalUA)2 was poorly induced by u(GalUA)2 or by D-galactu- digalacturonic acid ronan but produced wild-type levels of PL when supplied with 3- is shortened by adding 4,5-unsaturated deoxy-D-glycero-2,5-hexodiulosonic acid. PL synthesis. in the mu- [u(GalUA)2] and lengthened by adding EDTA, -which chelates tant could also be stimulated by 4,5-unsaturated trigalacturonic divalent cations essential for PL activity (8). PL synthesis is sub- acid, from which deoxyketuronic acid is released by another in- ject to cyclic AMP-controlled catabolite repression (9), and a tracellular enzyme. An OGL-deficient mutant that grew slowly on mutant deficient in cyclic AMP was similarly deficient in PL u(GalUA)2 in comparison with the wild-type parent was hyperin- (10). Finally, u(GalUA)2 at high concentrations exerts cyclic duced by u(GalUA)2 unless catabolite repression was relieved by AMP-reversible self-catabolite repression on PL (11). cyclic AMP or imposed by logarithmic growth on glycerol. PL syn- Our studies on the regulation ofthe PL produced by E. chry- thesis is also stimulated by saturated digalacturonic acid, which santhemi (12) suggested that saturated digalacturonic acid is released from D-galacturonan by another extracellular enzyme, [(GalUA)2], released by basal levels ofan extracellular exo-poly- exo-poly-a-D-galacturonosidase (EC 3.2.1.82). Because these di- a-D-galacturonosidase [PG; poly(1,4-a-D-galactosiduronate) mers stimulate PL synthesis at concentrations (wt/vol) 1/1000th digalacturonohydrolase, EC 3.2.1.82], could mediate induction ofthe concentration required by D-galacturonan, and because an on D-galacturonan even when u(GalUA)2 formation was blocked OGL-deficient mutantuninducible by dimers was also uninducible by EDTA (13). by D-galacturonan, we postulate that PL induction by pectic poly- Although the intracellular enzymes that degrade oligogalac- mers entails extracellular formation ofdimers and subsequent in- turonic acids have long been known (14-16), their involvement tracellular conversion to deoxyketuronic acids, the apparent in- in the regulation of extracellular PL has not been addressed. ducers of PL. To gain a deeper understanding of the induction and self-ca- tabolite repression of PL in E. chrysanthemi we identified the Several bacterial plant pathogens in the genus Erwinia are char- pectic intermediates formed during the conversion ofextracel- acterized by their ability to produce pectolytic enzymes and to lular D-galacturonan to an intracellular inducer of PL. and sup- macerate parenchymatous plant tissues. Our understanding of plied them to strains deficient in oligogalacturonide lyase (OGL; the relationship between these two capacities has become EC 4.2.2.6].The subsequent PL production of these mutants clearer in the past decade (1). Pectic polymers [chains of 1,4- indicates the importance ofthis intracellular enzyme in the reg- linked a-D-galacturonic acid (GalUA) and methoxylated deriv- ulation of extracellular PL. atives] are structural components of the middle lamellae and primary cell walls ofhigher plants (2, 3). Highly purified pectate MATERIALS AND METHODS lyase [PL; poly(1,4-a-D-galacturonide) lyase, EC 4.22.2], by its Origin and Growth of E. chrysanthemi Strains. CU 1, a action on this substrate, appears sufficient to account for both spontaneous mutant resistant to rifampicin (200 ,g/ml) and the maceration and the cell killing characteristics ofsoft rot dis- streptomycin (10 ,g/ml) was derived from E. chrysanthemi eases (4, 5). Evidence that PL production is necessary for ma- ceration has been reported for E. chrysanthemi; the capacity Abbreviations: PL, pectate lyase; GalUA, galacturonic acid; u(GalUA)2, for maceration and PL activity transfer together during conju- u(GalUA)3, and u(GalUA)4, di-, tri-, and tetragalacturonic acid 4,5-un- gation, suggesting that they are controlled by the same gene saturated at the nonreducing end; (GalUA)2, saturated digalacturonic (6). The apparent importance of pectic enzymes in the biology acid; PG, exo-poly-a-D-galacturonosidase; OGL, oligogalacturonide of their lyase; TBA, thiobarbituric acid; exoPL, exopolygalacturonate lyase; DK of these pathogens invites a thorough exploration I, 4-deoxy-L-threo-5-hexosulose uronic acid; DK II, 3-deoxy-D-glycero- regulation.