Linked Life Data

19667102

Source:http://linkedlifedata.com/resource/pubmed/id/19667102

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
10
pubmed:dateCreated
2009-10-9
pubmed:abstractText
The chloroplast-encoded Ycf4 plays an essential role in PSI complex assembly in the green alga Chlamydomonas reinhardtii. To gain insight into how Ycf4 functions, we generated several mutants in which residues R120, E179 and/or E181, which are conserved among oxygenic photosynthetic organisms, were changed to A or Q. Although the single mutants R120A and R120Q accumulated 80% less Ycf4 than the wild type, they assembled a functional PSI complex and grew photosynthetically like the wild type. Thus we inferred that under laboratory growth conditions, wild-type cells accumulate a superfluous amount of Ycf4. Single mutants E179A, E179Q and E181Q assembled a functional PSI complex like the wild type, whereas the single mutant E181A and double mutant E179/181A accumulated a functional PSI complex to significantly reduced levels. Double mutant E179/181Q, in contrast, accumulated Ycf4 at the wild-type level but did not assemble any mature PSI complex, suggesting that the two glutamic acid residues play crucial roles in the functionality of Ycf4. Interestingly, sucrose density gradient centrifugation of the thylakoid extracts separated a small amount of PSI subcomplex. The apparent size of the subcomplex (150-170 kDa), its composition and pulse-chase protein labeling indicate that it was an unstable subcomplex consisting of a PsaA-PsaB heterodimer. We inferred that the subcomplex was a PSI complex assembly intermediate that was detected because subsequent assembly steps were blocked by the E179/181Q mutation. We concluded that Ycf4 is involved in early processes of PSI complex assembly.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
1471-9053
pubmed:author
pubmed:issnType
Electronic
pubmed:volume
50
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1750-60
pubmed:meshHeading
pubmed:year
2009
pubmed:articleTitle
Effects of site-directed mutations in the chloroplast-encoded Ycf4 gene on PSI complex assembly in the green alga Chlamydomonas reinhardtii.
pubmed:affiliation
Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama, 700-8530, Japan.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't