Deletion mutations in a long hydrophilic loop in the photosystem II chlorophyll-binding protein CP43 in the cyanobacterium Synechocystis sp. PCC 6803

Matthias G. Kuhn, Willem Vermaas

Research output: Contribution to journalArticle

29 Scopus citations

Abstract

In order to investigate the role and function of the hydrophilic region between transmembrane regions V and CI in the photosystem II core antenna protein CP43, we introduced eight different deletions in psbC of Synechocystis sp; PCC 6803 resulting in a loss of 7-11 codons in evolutionary conserved domains in this region. All deletions resulted in an obligate photoheterotrophic phenotype (requirement of glucose for cell growth) and the absence of any detectable oxygen evolution activity. The various deletion mutations showed a different impact on the amount of CP43 in the thylakoid, ranging from wild-type levels of (a now slightly smaller) CP43 to no detectable CP43 at all. All deletions led to a decrease in the amount of the D1 and D2 proteins in the thylakoids with a larger effect on D2 than on D1. CP47, the other major chlorophyll-binding protein, was present in reduced but significant amounts in the thylakoid. Herbicide binding (diuron) was lost in all but one mutant indicating the PSII components are not assembled into functionally intact complexes. Fluorescence-emission spectra confirmed this notion. This indicates that the large hydrophilic loop of CP43 plays an important role in photosystem II, and even though a shortened CP43 is present in thylakoids of most mutants, functional characteristics resemble that of a mutant with interrupted psbC.

Original languageEnglish (US)
Pages (from-to)123-133
Number of pages11
JournalPlant Molecular Biology
Volume23
Issue number1
DOIs
StatePublished - Oct 1 1993

Keywords

  • Photosystem II
  • cyanobacteria
  • directed mutagenesis
  • psbC gene product

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Genetics
  • Plant Science

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