Linked Life Data

12767831

Source:http://linkedlifedata.com/resource/pubmed/id/12767831

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
2003-5-27
pubmed:abstractText
The EnvZ/OmpR histidyl-aspartyl phosphorelay (HAP) system in Escherichia coli regulates the expression of ompF and ompC, the major outer membrane porin genes, in response to environmental osmolarity changes. Here, we report that dimers of EnvZc, the cytoplasmic domain of EnvZ, undergo spontaneous subunit exchange in solution. By introducing a cysteine substitution (S260C) in the dimerization domain of EnvZc, we were able to crosslink the two subunits in a dimer and trap the heterodimer formed between two different mutant EnvZc. By using a complementing system with two autophosphorylation-defective EnvZc mutants, one containing the H243V mutation at the autophosphorylation site and the other containing the G405A mutation in the ATP-binding domain, we demonstrated that an EnvZc(G405A) subunit can be phosphorylated by an EnvZc(H243V) subunit only when a heterodimer is formed. The rate of subunit exchange is concentration-dependent, with higher rates at higher concentrations of protein. The disulfide-crosslinked EnvZc(G405A) homodimer could not be phosphorylated by EnvZc(H243V), since the heterodimer formation between the two mutant proteins was blocked, indicating that autophosphorylation cannot occur by dimer-dimer interaction. By using MBP-deltaL-EnvZc(S260C) fusion protein (deltaL: the linker region, spanning residues 180-222, was deleted), it was found that in the disulfide-crosslinked MBP-deltaL-EnvZc(S260C)/deltaL-EnvZc(S260C/G405A) heterodimer, only the deltaL-EnvZc(S260C/G405A) subunit was phosphorylated but not the MBP-deltaL-EnvZc(S260C) subunit. Together, the present results provide biochemical evidence that EnvZ autophosphorylation occurs in trans and only within an EnvZ dimer.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0022-2836
pubmed:author
pubmed:issnType
Print
pubmed:day
6
pubmed:volume
329
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
495-503
pubmed:dateRevised
2009-11-19
pubmed:meshHeading
pubmed:year
2003
pubmed:articleTitle
Spontaneous subunit exchange and biochemical evidence for trans-autophosphorylation in a dimer of Escherichia coli histidine kinase (EnvZ).
pubmed:affiliation
Department of Biochemistry, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, 675 Hoes Lane, Piscataway, NJ 08854-5635, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.