Linked Life Data

11882702

Source:http://linkedlifedata.com/resource/pubmed/id/11882702

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
Pt 3
pubmed:dateCreated
2002-3-7
pubmed:abstractText
Campylobacter jejuni is unable to utilize glucose as a carbon source due to the absence of the key glycolytic enzyme 6-phosphofructokinase. The genome sequence of C. jejuni NCTC 11168 indicates that homologues of all the appropriate enzymes for gluconeogenesis from phosphoenolpyruvate (PEP) are present, in addition to the anaplerotic enzymes pyruvate carboxylase (PYC), phosphoenolpyruvate carboxykinase (PCK) and malic enzyme (MEZ). Surprisingly, a pyruvate kinase (PYK) homologue is also present. To ascertain the role of these enzymes, insertion mutants in pycA, pycB, pyk and mez were generated. However, this could not be achieved for pckA, indicating that PCK is an essential enzyme in C. jejuni. The lack of PEP synthase and pyruvate orthophosphate dikinase activities confirmed a unique role for PCK in PEP synthesis. The pycA mutant was unable to grow in defined medium with pyruvate or lactate as the major carbon source, thus indicating an important role for PYC in anaplerosis. Sequence and biochemical data indicate that the PYC of C. jejuni is a member of the alpha4beta4, acetyl-CoA-independent class of PYCs, with a 65.8 kDa subunit containing the biotin moiety. Whereas growth of the mez mutant was comparable to that of the wild-type, the pyk mutant displayed a decreased growth rate in complex medium. Nevertheless, the mez and pyk mutants were able to grow with pyruvate, lactate or malate as carbon sources in defined medium. PYK was present in cell extracts at a much higher specific activity [>800 nmol x min(-1) x (mg protein)(-1)] than PYC or PCK [<65 nmol x min(-1) x (mg protein)(-1)], was activated by fructose 1,6-bisphosphate and displayed other regulatory properties strongly indicative of a catabolic role. It is concluded that PYK may function in the catabolism of unidentified substrates which are metabolized through PEP. In view of the high K(m) of MEZ for malate (approximately 9 mM) and the lack of a growth phenotype of the mez mutant, MEZ seems to have only a minor anaplerotic role in C. jejuni.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
1350-0872
pubmed:author
pubmed:issnType
Print
pubmed:volume
148
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
685-94
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2002
pubmed:articleTitle
Analysis of gluconeogenic and anaplerotic enzymes in Campylobacter jejuni: an essential role for phosphoenolpyruvate carboxykinase.
pubmed:affiliation
Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't