FEMS Yeast Research, 16, 2016, fow025 doi: 10.1093/femsyr/fow025 Advance Access Publication Date: 20 March 2016 Minireview MINIREVIEW Comparative analysis of sequences, polymorphisms Downloaded from https://academic.oup.com/femsyr/article/16/3/fow025/2467777 by guest on 30 September 2021 and topology of yeasts aquaporins and aquaglyceroporins Farzana Sabir1,2,∗,†, Maria C. Loureiro-Dias1 and Catarina Prista1 1LEAF, Instituto Superior de Agronomia, University of Lisbon, Tapada da Ajuda, 1349-017 Lisbon, Portugal and 2Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, University of Lisbon, 1649-003 Lisbon, Portugal ∗Corresponding author: LEAF, Instituto Superior de Agronomia, Universidade de Lisboa, Tapada da Ajuda, 1349-017 Lisboa, Portugal. Tel: (+351)-213653207; Fax: (+351)-213653195; E-mail: [email protected] One sentence summary: This review summarizes a detailed analysis of water and glycerol channels in yeasts and explores the relationship between their existence and adaptation of yeasts in various ecological niches. Editor: Jens Nielsen †Farzana Sabir, http://orcid.org/0000-0002-0181-989X ABSTRACT Efficient homeostasis of water and glycerol is a prerequisite for osmoregulation and other aspects of yeasts life. The cellular status of these molecules is often associated with functional presence of aquaporins and aquaglyceroporins. The present study provides a detailed updated analysis of aquaporins and aquaglyceroporins in 47 yeast species. A comprehensive analysis of aquaporins and aquaglyceroporins in 38 strains of Saccharomyces cerevisiae from different ecological niches is also presented. The functionality of specific aquaporins in yeasts has been associated with their adaptation requirements in different environmental conditions. In the present study, various inactivating mutations in aquaporin sequences were found in strains of S. cerevisiae. Likewise, several new interesting polymorphisms in aquaglyceroporin sequences of some commercial wine and brewing strains, vineyard and bakery strains were also observed. Conceivably, both in the case of aquaporins and aquaglyceroporins inactivating mutations resulted in competitive advantage in selected environments. Topology and conservation of important regulatory residues within all sequences are also analyzed. We expect that the present review may contribute to establish the functional relevance of aquaporins/aquaglyceroporins for various aspects of yeasts physiology. Keywords: Saccharomyces cerevisiae; yeasts; aquaporin; aquaglyceroporin; water transport INTRODUCTION rapid membrane water transport through water channels was suggested in mammalian red blood cells (Paganelli and Solomon Water equilibrium is a fundamental necessity of all living organ- 1957). Only after 30 years, the discovery by Agre and co-workers isms for maintenance of their cellular shape and turgor, and also of the first water channel in red blood cells known as aqua- for providing suitable conditions for various intracellular bio- porin 1 (AQP1) (Preston et al. 1992) popularized the concept of chemical processes. Formerly, simple diffusion through lipid bi- facilitated membrane water transport through aquaporins. Dur- layer was assumed to be the only mode of water flux in cells. In ing the following 20 years, numerous remarkable breakthroughs late 1950s, a vague idea of existence of an alternative route for Received: 7 February 2016; Accepted: 11 March 2016 C FEMS 2016. All rights reserved. For permissions, please e-mail: [email protected] 1 2 FEMS Yeast Research, 2016, Vol. 16, No. 3 have been achieved to understand the structural and func- The number of aquaporins present in various yeasts is gen- tional component of membrane water transport in almost all life erally restricted to one, with the exception of S. cerevisiae and forms including protozoa, bacteria, fungi, plants and animals Candida glabrata (Soveral et al. 2011). Retention of both genes of (Beitz 2005; Kaldenhoff and Fischer 2006; Kruse, Uehlein and orthodox aquaporins in S. cerevisiae is probably a consequence Kaldenhoff 2006; Nehls and Dietz 2014). Now, aquaporins are of the whole-genome duplication, resulting in the prototype unambiguously considered as the molecular component of fast with ∼10 000 genes (Wolfe and Shields 1997). Further, this an- reversible transmembrane water flux. They provide the unique cestor massively lost around 85% of duplicated copies, result- molecular entry point of water (Maurel and Chrispeels 2001), de- ing in modern-day species with ∼6000 genes, of which only pending on its chemical potential gradient (osmotic and/or hy- around 15% are duplicated copies. Why these remaining dupli- drostatic pressure) between either side of the membrane, and cated copies are still retained in the genome? Two possible func- their function seems crucial particularly at lower temperature tional fates have been proposed: (1) neo-functionalization, when (Soveral et al. 2006). They selectively allow rapid inward and out- the duplicated paralog acquires a novel function or altered reg- ward flux of uncharged water molecules while excluding ions ulatory responses, while the other one preserved the ancestral Downloaded from https://academic.oup.com/femsyr/article/16/3/fow025/2467777 by guest on 30 September 2021 and other solutes from passing through. Maintenance of cellu- function; (2) sub-functionalization, in which the functions of the lar volume and internal osmotic pressure, through aquaporin ancestral gene were distributed between the paralogs (Botstein gating, are regulated by various factors, such as pH, phospho- and Fink 2011). Expression analysis suggests that both yeast rylation, pressure, tension, solute gradients and temperature Aqy1 and Aqy2 are involved in similar but specific functions and (Chaumont, Moshelion and Daniels 2005; Leitao˜ et al. 2012; are somehow differently regulated (Ahmadpour et al. 2014). Soveral et al. 2006, 2008). The present review focuses on the occurrence of MIPs in var- Aquaporins belong to a highly conserved group of the major ious yeast species as well as in different strains of S. cerevisiae. intrinsic proteins (MIP) family, comprising more than 1700 in- Various polymorphisms in these sequences leading to inacti- tegral membrane proteins (Abascal, Irisarri and Zardoya 2014). vating mutations and non-functional alleles are explored. Their MIP-related proteins configure channels across the biological topology and regulatory domains are also analyzed. membrane to facilitate the bidirectional flux of water and small solutes like glycerol (Zardoya et al. 2002). MIP family members are divided in three groups: (1) aquaporins (orthodox, ordinary, GENES ENCODING MIPs SEQUENCES IN conventional or classical aquaporins); (2) aquaglyceroporins (un- YEASTS conventional or heterodox aquaporins); and (3) aquaporins with Genome sequencing studies have revealed that yeasts have unusual NPA (Asn-Pro-Ala) boxes (unorthodox, superaquaporins two putative orthodox aquaporins encoding genes, AQY1 (ORF or subcellular aquaporins). Members of aquaporin group specif- YPR192w)andAQY2 (ORF YLL052c-YLL053c) and two aquaglyc- ically facilitate water transport (Takata, Matsuzaki and Tajika eroporin encoding genes, FPS1 (ORF YLL043W)andYFL054C 2004), whereas aquaglyceroporins besides water majorly trans- (Bonhivers et al. 1998;Carbreyet al. 2001). For analyses of port glycerol (Luyten et al. 1995). Many lines of evidence sug- aquaglyceroporin sequences in the present study, we focused on gest that apart from glycerol, other small solutes, such as ar- Fps1, which is considered the main glycerol transporter (Nehls senite and antimony (Wysocki et al. 2001), acetic acid (Mol- and Dietz 2014). lapour and Piper 2007), ethanol (Teixeira et al. 2009), polyols Protein sequences of orthodox aquaporins (Aqy1 and Aqy2) (Karlgren et al. 2004) and boron (Nozawa et al. 2006), can also be and of aquaglyceroporin (Fps1) within the yeasts genome transported through aquaglyceroporins in yeasts. The third sub- were searched by BLASTp and tBLASTn tools from the avail- family, known as superaquaporins has been recently described able genome databases at Saccharomyces Genome Database and has been only found in multicellular organisms includ- (SGD, http://www.yeastgenome.org), Genolevures´ (http://www. ing nematodes, insects and vertebrates (Ishibashi, Tanaka and genolevures.org) and NCBI (http://www.ncbi.nlm.nih.gov). Ob- Morishita 2014). In mammals they have been found in kidney, tained sequences were compared with the sequences of func- liver, sperm, thymus and brain cells at the membranes of in- tional versions of orthodox aquaporins and aquaglyceroporin tracellular organelles like lysosome, mitochondria and endo- proteins of S. cerevisiae 1278B strain. Detailed compilations of plasmic reticulum. Although their exact function is still un- MIP sequences obtained in the genomes of 47 yeast species and known, studies indicate their role in intracellular water trans- of 38 strains of S. cerevisiae identified from various niches are port (Ishibashi, Tanaka and Morishita 2014). presented in Tables 1 and 2, respectively. Sequences annotated Yeasts are important life forms for humans; their association in this study were designated according to their higher percent- to mankind is as ancient as the history of bread, beer and wine. age identity with ScAqy1, ScAqy2 or ScFps1. All the complete or- They have enormous economical impact through the commer- thodox aquaporins and aquaglyceroporin sequences were used