Linked Life Data

10594816

Source:http://linkedlifedata.com/resource/pubmed/id/10594816

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
2000-2-11
pubmed:abstractText
The 110 kDa haemolysin protoxin (proHlyA) is activated in the Escherichia coli cytosol by acyl carrier protein-dependent fatty acylation of two internal lysine residues, directed by the co-synthesized protein HlyC. Using an in vitro maturation reaction containing purified protoxin peptides and acylACP, we show unambiguously that HlyC possesses an apparently unique acyltransferase activity fully described by Michaelis-Menten analysis. The Vmax of HlyC at saturating levels of both substrates was approximately 115 nmol acyl group min-1 mg-1 with KMacylACP of 260 nM and KMproHlyA of 27 nM, kinetic parameters sufficient to explain why in vivo HlyC is required at a concentration equimolar to proHlyA. HlyC bound the fatty acyl group from acylACP to generate an acylated HlyC intermediate that was depleted in the presence of proHlyA, but enriched in the presence of proHlyA derivatives lacking acylation target sites. HlyC was also able to bind in vivo 4'-phosphopantetheine. Substitution of conserved amino acids that could act as putative covalent attachment sites did not prevent binding of the fatty acyl or 4'-phosphopantetheine groups. These data and substrate variation analyses suggest that the unique acylation reaction does not involve covalent attachment of fatty acid to the acyltransferase, but rather that it proceeds via a sequential ordered Bi-Bi reaction mechanism, requiring the formation of a non-covalent ternary acylACP-HlyC-proHlyA complex.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0950-382X
pubmed:author
pubmed:issnType
Print
pubmed:volume
34
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
887-901
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
An ordered reaction mechanism for bacterial toxin acylation by the specialized acyltransferase HlyC: formation of a ternary complex with acylACP and protoxin substrates.
pubmed:affiliation
Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK. plds1@mole.bio.cam.ac.uk
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't