Regulatory potential, phyletic distribution and evolution of ancient, intracellular small-molecule-binding domains.
Central cellular functions such as metabolism, solute transport and signal transduction are regulated, in part, via binding of small molecules by specialized domains. Using sensitive methods for sequence profile analysis and protein structure comparison, we exhaustively surveyed the protein sets from completely sequenced genomes for all occurrences of 21 intracellular small-molecule-binding domains (SMBDs) that are represented in at least two of the three major divisions of life (bacteria, archaea and eukaryotes). These included previously characterized domains such as PAS, GAF, ACT and ferredoxins, as well as three newly predicted SMBDs, namely the 4-vinyl reductase (4VR) domain, the NIFX domain and the 3-histidines (3H) domain. Although there are only a limited number of different superfamilies of these ancient SMBDs, they are present in numerous distinct proteins combined with various enzymatic, transport and signal-transducing domains. Most of the SMBDs show considerable evolutionary mobility and are involved in the generation of many lineage-specific domain architectures. Frequent re-invention of analogous architectures involving functionally related, but not homologous, domains was detected, such as, fusion of different SMBDs to several types of DNA-binding domains to form diverse transcription regulators in prokaryotes and eukaryotes. This is suggestive of similar selective forces affecting the diverse SMBDs and resulting in the formation of multidomain proteins that fit a limited number of functional stereotypes. Using the "guilt by association approach", the identification of SMBDs allowed prediction of functions and mode of regulation for a variety of previously uncharacterized proteins.
Anantharaman
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V
National Center for Biotechnology Information National Library of Medicine, National Institutes of Health, Bethesda, MD, 20894, USA.
Koonin
E V
EV
Aravind
L
L
D000595:Amino Acid Sequence; D000818:Animals; D019843:Archaeal Proteins / Q000737:chemistry / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism; D019295:Computational Biology; D004798:Enzymes / Q000737:chemistry / Q000378:metabolism; D005057:Eukaryotic Cells / Q000737:chemistry; D019143:Evolution, Molecular; D016678:Genome; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010802:Phylogeny; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism*; D020917:Receptor, trkA; D016415:Sequence Alignment; D015398:Signal Transduction; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism
D019843:Archaeal Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D004798:Enzymes; D008565:Membrane Proteins; D011506:Proteins; D014157:Transcription Factors; D020917:Receptor, trkA