The maize chloroplast genes for the β and ε subunits of the photosynthetic factor CF₁are fused

Abstract

We have cloned and sequenced the maize chloroplast genome fragment Eco RI e which contains the 2.2 kb transcript previously reported (Link, G. and Bogorad, L. (1980) Proc. Nat. Acad. Sci. 77 6821-6825) to lie next to the maize gene for the large subunit of ribulose bisphosphate carboxylase (LS) and to be transcribed divergently. Immunochemical and sequencing data show that the gene codes for the beta subunit of the maize chloroplast coupling factor complex (CF1). The derived amino acid sequence is highly homologous to that of the corresponding E. coli protein (Saraste et al. (1981) Nucleic Acids Res. 9 5287-5296). The last base of the codon for the terminal lysine residue of the beta subunit of CF1 is the first base of the codon for the initiating methionine of an open reading frame whose derived amino acid composition and size closely match that reported for the epsilon subunit (Binder et al. (1978) J. Biol. Chem. 253 3094-3100). The close coupling of the two genes may serve to in sure their stoichiometric production.

Nuclear Gene-Regulated Expression of Chloroplast Genes for Coupling Factor One in Maize

“…Similar hybridization results were obtained with RNAs from both wild-type maize and mutant hcft-38 using portions of DNAs coding for 13 and e subunits of CF, (13 and e subunits are encoded in a co-transcribed mRNA [13]), QB protein, and the large subunit of RuBP carboxylase as probes (Fig. 5A).…”

“…The nuclear gene maize mutant designated hcft-38 (25) is shown in this communication to be deficient in a and 13 subunits of CF,. These subunits are products of plastid genes in maize (13,26).…”

“…Some peptides, such as the a and 13 subunits of CF, (6,13) which are in relatively low abundance in mutant hcf*-38 thylakoids, as summarized in Table I Fig. 1 for a restriction map of maize chloroplast DNA) were visible when lower concentrations of mutant RNA was used for prehybridization preceding hybridization with radioactive RNA ofwild-type plants (Fig.…”

“…These subunits are products of plastid genes in maize (13,26). The present investigation was directed at understanding the basis for the very low levels of the protein products of the two plastid genes in this nuclear gene mutant.…”

Identification and partial DNA sequence of the gene for the α‐subunit of the ATP synthase complex of Chlamydomonas reinhardii chloroplasts

“…Like its mitochondrial and bacterial counterparts, the CFo-CFI complex catalyzes the synthesis of ATP in response to a proton flux across the photosynthetic membranes. The chloroplast ATP synthase consists of at least 8 polypeptides, including 3 CFo components designated [5][6]. In spinach chloroplasts, three of the CF1 subunits ((u, p, and 6) and two CFo subunits (polypeptides I and III) are encoded in the plastid DNA and synthesized on chloroplast ribosomes.…”