Site-directed mutagenesis and analysis of second-site revertants indicates a requirement for C-terminal amino acids of PsaB for stable assembly of the photosystem I reaction center complex in chlamydomonas reinhardtii

Hyeonmoo Lee, Scott E. Bingham, Andrew Webber

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

The PsaA and PsaB polypeptides form the reaction center core heterodimer of photosystem I (PSI). Both PsaA and PsaB are predicted to have 11 hydrophobic domains, although it is unclear how both polypeptides fold within the thylakoid membrane. If all 11 hydrophobic regions form membrane-spanning domains, the N- and C-terminus must be located on opposite sides of the membrane. The C-terminus of PsaB is very conserved in a wide range of organisms and may be important for PSI assembly or function. Using chloroplast transformation in Chlamydomonas reinhardtii we have generated a series of C-tcrminal extension and deletion mutants of the PsaB polypeptide. Analysis of these mutants and spontaneous revertants indicates that the C-terminus may be extended by at least 14 amino acids without impairing PSI assembly. Deletion of amino acids 732-736 also has no impact on PSI, whereas deletion of amino acids 727-736 results in no accumulation of the complex. The site of truncation in the 727-736 deletion coincides with the end of the hydrophobic domain XI supporting a location of the C-terminus of PsaB on the lumenal side of PSI.

Original languageEnglish (US)
Pages (from-to)46-52
Number of pages7
JournalPhotochemistry and photobiology
Volume64
Issue number1
DOIs
StatePublished - Jan 1 1996

ASJC Scopus subject areas

  • Biochemistry
  • Physical and Theoretical Chemistry

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