Tomio Terao

Turnover of LHC-I and LHC-II Apoproteins in Chl b-Deficient Mutants of Rice and Barley

Chl b is an important photosynthetic pigment which is exclusively present in light-harvesting Chl a/b-proteins, LHC-I and LHC-II1). LHC-I and LHC-II are totally absent from mutants which lack Chl b 2)3)4). A Chl b-less barley mutant, ‘chlorina f2’, has the capability of synthesizing precursors of LHC apoproteins and assembling them into thylakoid membrane5). However the mutant thylakoids contain very low levels of LHC-I and LHC-II apoproteins and one or two of major apoproteins have been reported to be missing6)7)8). We also showed that Chl b-less rice chlorina mutants contained mRNA for apoprotein of LHC-II. All the five proteins related to LHC-I and LHC-II are present but in reduced amounts9). These observation led to a suggestion that newly synthesized apoproteins are stabilized only when they are associated with Chl b 5). To examine this possibility, we have measured the synthesis and turnover of the apoproteins of LHC-I and LHC-II in Chl b-less mutants of rice and barley.