|Gene:||pgaB||Accession Numbers: G6530 (MetaCyc), b1023, ECK1013|
Synonyms: hmsF, ycdR
Species: Escherichia coli K-12 substr. MG1655
PgaB is an outer membrane lipoprotein that is required for the partial de-N-acetylation and transport of poly-β-1,6-N-acetyl-D-glucosamine (known as PGA or PNAG) - an exopolysaccharide that is a key component of the biofilm matrix of several medically important bacteria [Wang04a, Itoh05, Itoh08].
PgaB consists of an N-terminal domain that forms a (β/α)7 barrel structure and belongs to the class 4 carbohydrate esterases and a C-terminal domain that forms a (β/α)8 barrel and contains a flexible β hairpin loop [Little12]. Both domains are necessary for de-N-acetylation of PNAG; PNAG binds to a cleft formed between the N and C-terminal domains in an extended conformation [Little14].
PgaB is a metal dependent de-N-acetylase with a preference for Co2+, Ni2+ and Fe2+; PgaB binds two metal ions per molecule; PgaB has specificity for PNAG oligomers [Little12]
pgaB is part of a 4 gene locus (pgaABCD) whose gene products are involved in the synthesis, modification and export of PNAG. Expression of pgaABCD is higher at 37°C than at 21°C and is highest during stationary phase [Cerca08]. Expression also increased in response to one-percent NaCl or ethanol [Cerca08]. Expression increased in response to glucose, ethanol, NaCl, and MnCl2 in a clinical isolate, and dramatically increased upon deletion or mutation of csrA in this strain [Cerca08, Mercante06]. CsrA inhibits translation of pgaABCD mRNA by binding to six sites within the pgaABCD leader [Wang05b, Mercante06]. NaCl and alkaline pH induction are dependent upon nhaR as deletion of this gene prevented induction [Goller06, Cerca08].
PgaB has similarity to the HmsF protein encoded by the Yersinia pestis hmsHFRST gene cluster, which is involved in plague transmission [Jones99a].
Locations: outer membrane
|Map Position: [1,087,062 <- 1,089,080]|
Molecular Weight of Polypeptide: 77.413 kD (from nucleotide sequence)
Unification Links: ASAP:ABE-0003467 , DIP:DIP-11513N , EchoBASE:EB3624 , EcoGene:EG13864 , EcoliWiki:b1023 , ModBase:P75906 , OU-Microarray:b1023 , PortEco:pgaB , Protein Model Portal:P75906 , RefSeq:NP_415542 , RegulonDB:G6530 , SMR:P75906 , String:511145.b1023 , UniProt:P75906
Relationship Links: InterPro:IN-FAMILY:IPR002509 , InterPro:IN-FAMILY:IPR011330 , InterPro:IN-FAMILY:IPR023854 , PDB:Structure:3VUS , PDB:Structure:4F9D , PDB:Structure:4F9J , Pfam:IN-FAMILY:PF01522 , Prosite:IN-FAMILY:PS51257 , Prosite:IN-FAMILY:PS51677
|Biological Process:||GO:0042710 - biofilm formation
GO:0098732 - macromolecule deacylation [Itoh08, Little12]
GO:0005975 - carbohydrate metabolic process [GOA01a]
|Molecular Function:||GO:0016810 - hydrolase activity, acting on carbon-nitrogen (but not peptide) bonds
[GOA01a, Itoh08, Little12]
GO:0003824 - catalytic activity [GOA01a]
GO:0016787 - hydrolase activity [UniProtGOA11a]
|Cellular Component:||GO:0009279 - cell outer membrane
GO:0016020 - membrane [UniProtGOA11a]
GO:0031246 - intrinsic component of periplasmic side of cell outer membrane [Itoh08, Wang04a]
|MultiFun Terms:||metabolism → biosynthesis of macromolecules (cellular constituents)|
Enzymatic reaction of: poly-β-1,6-N-acetyl-D-glucosamine N-deacetylase
The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction in which it was curated.
Reversibility of this reaction is unspecified.
|Feature Class||Location||Common Name||Citations||Comment|
|Signal-Sequence||1 -> 20||PgaB signal sequence|
|Chain||21 -> 672|
|Lipid-Binding-Site||21||PgaB palmitoylation site|
|Conserved-Region||107 -> 349|
Markus Krummenacker on Tue Oct 14, 1997:
Gene object created from Blattner lab Genbank (v. M52) entry.
Agladze05: Agladze K, Wang X, Romeo T (2005). "Spatial periodicity of Escherichia coli K-12 biofilm microstructure initiates during a reversible, polar attachment phase of development and requires the polysaccharide adhesin PGA." J Bacteriol 187(24);8237-46. PMID: 16321928
Goller06: Goller C, Wang X, Itoh Y, Romeo T (2006). "The cation-responsive protein NhaR of Escherichia coli activates pgaABCD transcription, required for production of the biofilm adhesin poly-beta-1,6-N-acetyl-D-glucosamine." J Bacteriol 188(23);8022-32. PMID: 16997959
Itoh05: Itoh Y, Wang X, Hinnebusch BJ, Preston JF, Romeo T (2005). "Depolymerization of beta-1,6-N-acetyl-D-glucosamine disrupts the integrity of diverse bacterial biofilms." J Bacteriol 187(1);382-7. PMID: 15601723
Itoh08: Itoh Y, Rice JD, Goller C, Pannuri A, Taylor J, Meisner J, Beveridge TJ, Preston JF, Romeo T (2008). "Roles of pgaABCD genes in synthesis, modification, and export of the Escherichia coli biofilm adhesin poly-beta-1,6-N-acetyl-D-glucosamine." J Bacteriol 190(10);3670-80. PMID: 18359807
Little12: Little DJ, Poloczek J, Whitney JC, Robinson H, Nitz M, Howell PL (2012). "The structure- and metal-dependent activity of Escherichia coli PgaB provides insight into the partial de-N-acetylation of poly-β-1,6-N-acetyl-D-glucosamine." J Biol Chem 287(37);31126-37. PMID: 22810235
Little14: Little DJ, Li G, Ing C, DiFrancesco BR, Bamford NC, Robinson H, Nitz M, Pomes R, Howell PL (2014). "Modification and periplasmic translocation of the biofilm exopolysaccharide poly-β-1,6-N-acetyl-D-glucosamine." Proc Natl Acad Sci U S A 111(30);11013-8. PMID: 24994902
Mercante06: Mercante J, Suzuki K, Cheng X, Babitzke P, Romeo T (2006). "Comprehensive alanine-scanning mutagenesis of Escherichia coli CsrA defines two subdomains of critical functional importance." J Biol Chem 281(42);31832-42. PMID: 16923806
Wang04a: Wang X, Preston JF, Romeo T (2004). "The pgaABCD locus of Escherichia coli promotes the synthesis of a polysaccharide adhesin required for biofilm formation." J Bacteriol 186(9);2724-34. PMID: 15090514
Wang05b: Wang X, Dubey AK, Suzuki K, Baker CS, Babitzke P, Romeo T (2005). "CsrA post-transcriptionally represses pgaABCD, responsible for synthesis of a biofilm polysaccharide adhesin of Escherichia coli." Mol Microbiol 56(6);1648-63. PMID: 15916613
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