scholarly journals Ice‐binding proteins from the fungusAntarctomyces psychrotrophicuspossibly originate from two different bacteria through horizontal gene transfer

FEBS Journal ◽  
2018 ◽  
Vol 286 (5) ◽  
pp. 946-962 ◽  
Author(s):  
Tatsuya Arai ◽  
Daichi Fukami ◽  
Tamotsu Hoshino ◽  
Hidemasa Kondo ◽  
Sakae Tsuda
Keyword(s):  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Binding Proteins ◽  
Ice Binding

scholarly journals Several Archaeal Homologs of Putative Oligopeptide-Binding Proteins Encoded by Thermotoga maritima Bind Sugars

2006 ◽  
Vol 72 (2) ◽  
pp. 1336-1345 ◽  
Author(s):  
Dhaval M. Nanavati ◽  
Kamolwan Thirangoon ◽  
Kenneth M. Noll
Keyword(s):  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Abc Transporters ◽  
Binding Proteins ◽  
Thermotoga Maritima ◽  
Substrate Binding ◽  
Carbon And Nitrogen ◽  
Selective Pressures ◽  
Hyperthermophilic Bacterium ◽  
Substrate Affinities

ABSTRACT The hyperthermophilic bacterium Thermotoga maritima has shared many genes with archaea through horizontal gene transfer. Several of these encode putative oligopeptide ATP binding cassette (ABC) transporters. We sought to test the hypothesis that these transporters actually transport sugars by measuring the substrate affinities of their encoded substrate-binding proteins (SBPs). This information will increase our understanding of the selective pressures that allowed this organism to retain these archaeal homologs. By measuring changes in intrinsic fluorescence of these SBPs in response to exposure to various sugars, we found that five of the eight proteins examined bind to sugars. We could not identify the ligands of the SBPs TM0460, TM1150, and TM1199. The ligands for the archaeal SBPs are TM0031 (BglE), the β-glucosides cellobiose and laminaribiose; TM0071 (XloE), xylobiose and xylotriose; TM0300 (GloE), large glucose oligosaccharides represented by xyloglucans; TM1223 (ManE), β-1,4-mannobiose; and TM1226 (ManD), β-1,4-mannobiose, β-1,4-mannotriose, β-1,4-mannotetraose, β-1,4-galactosyl mannobiose, and cellobiose. For comparison, seven bacterial putative sugar-binding proteins were examined and ligands for three (TM0595, TM0810, and TM1855) were not identified. The ligands for these bacterial SBPs are TM0114 (XylE), xylose; TM0418 (InoE), myo-inositol; TM0432 (AguE), α-1,4-digalactouronic acid; and TM0958 (RbsB), ribose. We found that T. maritima does not grow on several complex polypeptide mixtures as sole sources of carbon and nitrogen, so it is unlikely that these archaeal ABC transporters are used primarily for oligopeptide transport. Since these SBPs bind oligosaccharides with micromolar to nanomolar affinities, we propose that they are used primarily for oligosaccharide transport.

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