Bacterial high affinity transport systems are involved in active transport of solutes across the cytoplasmic membrane. Most of the bacterial ABC (ATP-binding cassette) importers are composed of one or two transmembrane permease proteins, one or two nucleotide-binding proteins and a highly specific periplasmic solute-binding protein. In Gram-negative bacteria the solute-binding proteins are dissolved in the periplasm, while in archaea and Gram-positive bacteria, their solute-binding proteins are membrane-anchored lipoproteins [, ]. On the basis of sequence similarities, the vast majority of these solute-binding proteins can be grouped into eight family clusters [], which generally correlate with the nature of the solute bound. This entry represents the family 1. Family 1 members include:Maltose/maltodextrin-binding proteins of Enterobacteriaceae (gene malE) []and Streptococcus pneumoniae malXMultiple oligosaccharide binding protein of Streptococcus mutans (gene msmE)Escherichia coli glycerol-3-phosphate-binding proteinSerratia marcescens iron-binding protein (gene sfuA) and the homologous proteins (gene fbp) from Haemophilus influenzae and NeisseriaE. coli thiamine-binding protein (gene tbpA) Interestingly, these thiamin-binding proteins share protein structural similarity with thiaminase-I. They may be evolved from a common ancestor []. This entry also includes thiaminase-1 from Paenibacillus thiaminolyticus (Bacillus thiaminolyticus).
SBP (for SQUAMOSA-pROMOTER BINDING PROTEIN) domain is a sequence specific DNA-binding domain found in plant proteins []. Members of family probably function as transcription factors involved in the control of early flower development []. They share a highly conserved DNA-binding domain that contains two zinc-binding sites. Among the 11 possible ligands for the zinc atoms that are conserved in the SBP zinc finger, only 8 are used. The SBP zinc finger follows the general pattern C-x4-C-x16-C-x2-[HC]-x15-C-x2-C-x3-H-x11-C. Three other histidines are well conserved but not involved in zinc binding [, ].In vitro experiments show that the SBP zinc finger preferentially binds theconsensus sequence -TNCGTACAA- []. However, little is known of the physiological functions of these putative transcriptional regulators beyond their ability to bind DNA.The solution structure of the SBP zinc finger has been solved[]. The first four Cys or His coordinate one zinc ion and the last four coordinate the other. It can be viewed as two structural subdomains, each subdomain containing a single zinc-binding pocket. The N-terminal subdomain consists of two short alpha helices whereas the C-terminal one contains a three-stranded antiparallel β-sheet.
SBP (for SQUAMOSA-pROMOTER BINDING PROTEIN) domain is a sequence specific DNA-binding domain found in plant proteins []. Members of family probably function as transcription factors involved in the control of early flower development []. They share a highly conserved DNA-binding domain that contains two zinc-binding sites. Among the 11 possible ligands for the zinc atoms that are conserved in the SBP zinc finger, only 8 are used. The SBP zinc finger follows the general pattern C-x4-C-x16-C-x2-[HC]-x15-C-x2-C-x3-H-x11-C. Three other histidines are well conserved but not involved in zinc binding [, ].In vitro experiments show that the SBP zinc finger preferentially binds theconsensus sequence -TNCGTACAA- []. However, little is known of the physiological functions of these putative transcriptional regulators beyond their ability to bind DNA.The solution structure of the SBP zinc finger has been solved[]. The first four Cys or His coordinate one zinc ion and the last four coordinate the other. It can be viewed as two structural subdomains, each subdomain containing a single zinc-binding pocket. The N-terminal subdomain consists of two short alpha helices whereas the C-terminal one contains a three-stranded antiparallel β-sheet.
The tripartite ATP-independent periplasmic (TRAP) transporters are substrate-binding protein (SBP)-dependent secondary transporters ubiquitous in prokaryotes, but absent from eukaryotes. Theyare comprised of an SBP of the DctP or TAXI families and two integral membrane proteins of unequal sizes that form the DctQ and DctM protein families (the small and large membrane components respectively). The TRAP transporter for sialic acid consists of the SBP siaP, and siaQM (termed siaT in some cases), encoding the fused integral membrane protein [].This family consists of DctQ homologues found in TRAP transporters [].
This entry represents a group of DNA binding proteins, known as SBP (SQUAMOSA-PROMOTER BINDING PROTEIN) family. They are putative transcription factors characterised by a highly conserved SBP-box of 76 amino acids involved in DNA binding and nuclear localisation []. They are involved in the control of early flower development [].
This entry represents a group of DNA binding proteins, known as SBP (SQUAMOSA-pROMOTER BINDING PROTEIN) family. They are putative transcription factors characterised by a highly conserved SBP-box of 76 amino acids involved in DNA binding and nuclear localisation []. They are involved in the control of early flower development []. This entry includes Arabidopsis SPL3 and SPL4 []. SPL3/SPL4 promote vegetative phase change and flowering, and are strongly repressed by miR156 [].
Sulphate-binding protein (gene sbp or sbpA) and thiosulphate-binding protein (gene cysP) are two structurally related periplasmic bacterial proteins which specifically bind sulphate and thiosulphate and are involved in the transport systems for these nutrients [, ]. There are two conserved regions in the protein, one located in the N-terminal region and the other in the central part of these proteins. The second region includes two adjacent amino acids (Ser-Gly) that, in sbp, are known to be essential for sulphate binding [].This entry represents a conserved site located in the N-terminal region of these proteins.
Sulphate-binding protein (gene sbp or sbpA) and thiosulphate-binding protein (gene cysP) are two structurally related periplasmic bacterial proteins which specifically bind sulphate and thiosulphate and are involved in the transport systems for these nutrients [, ]. There are two conserved regions in the protein, one located in the N-terminal region and the other in the central part of these proteins. The second region includes two adjacent amino acids (Ser-Gly) that, in sbp, are knownto be essential for sulphate binding [].This entry represents the second conserved region that includes two adjacent amino acids (Ser-Gly) known to be essential for sulfate binding [].
