Cloning and characterization of the nuclear AC115 gene of Chlamydomonas reinhardtii

• Published in: Plant molecular biology Vol. 39; no. 1; pp. 1 - 10
• Main Authors: Rattanachaikunsopon, P, Rosch, C, Kuchka, M.R
• Format: Journal Article
• Language: English
• Published: Netherlands Springer Nature B.V 1999
• Subjects: Algal Proteins; Amino Acid Sequence; amino acid sequences; Amino acids; Animals; Base Sequence; Biological Transport - genetics; Blotting, Southern; Chlamydomonas reinhardtii; Chlamydomonas reinhardtii - genetics; chloroplast transit sequence; chloroplasts; Cloning; Cloning, Molecular; complementary DNA; Cosmids; Deoxyribonucleases, Type II Site-Specific - metabolism; DNA, Plant - chemistry; DNA, Protozoan - chemistry; Freshwater; genbank/af045466; genbank/af045467; Genes; Molecular Sequence Data; mutants; Nuclear Proteins - chemistry; Nuclear Proteins - genetics; nucleotide sequences; open reading frames; Photosynthetic Reaction Center Complex Proteins - metabolism; Photosystem II Protein Complex; Plant Proteins; polypeptides; Proteins; signal peptide; structural genes
• ISSN: 0167-4412; 1573-5028
• DOI: 10.1023/A:1006108203580

The nuclear ac115 mutant of Chlamydomonas reinhardtii is specifically blocked in the synthesis of the chloroplast encoded D2 protein of the photosystem II reaction center at a point after translation initiation. Here, we report the identification of the AC115 gene through complementation rescue of the ac115 mutant strain, using an indexed cosmid library of Chlamydomonas genomic DNA. AC115 is a small, novel, intronless nuclear gene which encodes a protein of 113 amino acids. The amino terminal end of the Ac115 protein is rich in basic amino acids and has features which resemble a chloroplast transit sequence. A hydrophobic stretch of amino acids at the protein's carboxyl terminus is sufficiently large to be a membrane spanning or a protein/protein interaction domain. Various models are discussed to account for the mechanism by which Ac115p works in D2 synthesis. The ac115 mutant allele was sequenced and determined to be an A-to-T transversion at the first position of the fourth codon of the coding sequence. This mutation changes an AAG codon to a TAG nonsense codon and results in a null phenotype.