Linked Life Data

9468498

Source:http://linkedlifedata.com/resource/pubmed/id/9468498

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
8
pubmed:dateCreated
1998-3-19
pubmed:abstractText
Dictyostelium discoideum (Amoebidae) secretes cell-lysing enzymes: esterases, amidases, and glycosylases, many of which degrade soil bacteria to provide a source of nutrients. Two of these enzymes, fatty-acyl amidases FAA I and FAA II, act sequentially on the N-linked long chain acyl groups of lipid A, the lipid anchor of Gram-negative bacterial lipopolysaccharide. FAA I selectively hydrolyzes the 3-hydroxymyristoyl group N-linked to the proximal glucosamine residue of de-O-acylated lipid A. Substrate specificity for FAA II is less selective, but does require prior de-N-acylation of the proximal sugar, i.e. bis-N-acylated lipid A is not a substrate. We have synthesized a 14C-labeled substrate analog for FAA II and used this in a novel assay to monitor its purification. Inhibitory studies indicate that FAA II is not a serine protease, but may have a catalytic mechanism similar to metalloprotein de-N-acetylases such as LpxC. Interestingly, rhizobial Nod factor signal oligosaccharides that induce root nodules on leguminous plants have many of the structural requirements for substrate recognition by FAA II. In vitro evidence indicates that Rhizobium fredii Nod factors are selectively de-N-acylated by purified FAA II, suggesting that the enzyme may reduce the N2-fixing efficiency of Rhizobium-legume symbioses. In contrast, N-methylated Nod factors from transgenic R. fredii carrying the rhizobial nodS gene were resistant to FAA II, suggesting a mechanism by which Nod factors may be protected from enzymatic de-N-acylation. Since FAA II and Nod factors are both secreted, and Nod factors that lack the N-acyl group are unable to induce nodules, dictyostelial FAA II may decrease the efficiency of symbiotic nitrogen fixation in the environment by reducing the available biologically active nodule inducer signal.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
20
pubmed:volume
273
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
4459-64
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Dictyostelium discoideum fatty-acyl amidase II has deacylase activity on Rhizobium nodulation factors.
pubmed:affiliation
Department of Chemistry, College of Environmental Science and Forestry, State University of New York, Syracuse, New York 13210, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't