Linked Life Data

18415008

Source:http://linkedlifedata.com/resource/pubmed/id/18415008

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2008-5-23
pubmed:abstractText
Pairs of cysteine residues were introduced into the twisted N- and C-terminal helices of the gamma subunit of the chloroplast F1-ATPase to test, via disulfide cross-linking, potential inter-helical movements involved in catalysis of ATP hydrolysis. The extent of disulfide cross-linking was determined by estimating the amount of free sulfhydryl available for labeling with fluoresceinyl maleimide before and after cross-linking. Significant disulfide formation (50-75%) was observed between cysteines introduced at positions 30 and 31 in the N-terminal helix and 276 and 278 in the C-terminal helix. Cross-linking had no apparent effect on catalysis, therefore eliminating the involvement of large-scale inter-helical movements within this region of the gamma subunit in cooperative ATP hydrolysis. However, the presence of the two cysteines together in the gammaV31C/A276C double mutant, irrespective of whether or not they were cross-linked together, lowered the MgATPase activity by more than 70% and completely eliminated the well-known activating effect of the oxyanion sulfite. The CaATPase activity was unaffected. Similar but less pronounced effects were seen with the gammaK30C/A276C double mutant. The results indicate that residues at or near positions 31 and 276 within the twisted helical pair of the gamma subunit are required to overcome Mg2+ inhibition of ATP hydrolysis. These residues are likely to be involved in forming a point of contact between the gamma and beta subunits that is responsible for this effect.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0145-479X
pubmed:author
pubmed:issnType
Print
pubmed:volume
40
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
69-76
pubmed:meshHeading
pubmed:year
2008
pubmed:articleTitle
The role of specific beta-gamma subunit interactions in oxyanion stimulation of the MgATP hydrolysis of a hybrid photosynthetic F1-ATPase.
pubmed:affiliation
Department of Molecular Biosciences, The University of Kansas, 1200 Sunnyside Ave., Lawrence, KS 66045, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, N.I.H., Extramural