Structure and targeted mutagenesis of the gene encoding 8-kDa subunit of photosystem I from the cyanobacterium Synechocystis sp. PCC 6803.

P. R. Chitnis*, P. A. Reilly, M. C. Miedel, N. Nelson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

93 Scopus citations

Abstract

Photosystem I reaction center of the cyanobacterium Synechocystis sp. PCC 6803 contains seven different polypeptide subunits. The subunit with a molecular mass of about 8 kDa was isolated, and the sequence of its amino-terminal residues was determined. Oligonucleotide probes corresponding to this sequence were used to isolate the gene encoding this subunit. The gene, termed as psaE, codes for a polypeptide with a mass of 8075 Da. It is present as a single copy in the genome and is transcribed as a monocistronic messenger. The amino acid sequence of the 8-kDa subunit deduced from the gene sequence shows high homology with the deduced amino acid sequence of subunit IV of photosystem I from spinach. The DNA fragment sequenced in these studies also contains two other unidentified major open reading frames. A stable deletion mutation for the psaE gene was generated by transforming Synechocystis sp. PCC 6803 with a cloned DNA in which the psaE gene for 8-kDa subunit was replaced by a gene conferring resistance to kanamycin. The mutant strain shows minor differences in growth under photoautotrophic conditions and in the photosystem I activity in comparison to the wild type.

Original languageEnglish
Pages (from-to)18374-18380
Number of pages7
JournalThe Journal of biological chemistry
Volume264
Issue number31
DOIs
StatePublished - 5 Nov 1989
Externally publishedYes

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