Đang chuẩn bị nút TẢI XUỐNG, xin hãy chờ
Tải xuống
Genes homologous to hydrogenase accessory genes are scattered over the whole genome in the cyanobacteriumSynechocystissp. PCC 6803. Deletion and insertion mutants of hypA1 (slr1675), hypB1 (sll1432), hypC, hypD, hypE and hypF were constructed and showed no hydrogenase activity. Involvement of the respective genes in maturation of the enzyme was con-firmed by complementation. Deletion of the additional homologueshypA2 (sll1078) and hypB2(sll1079) had no effect on hydrogenase activity. Thus, hypA1andhypB1are specific for hydrogenase maturation | ễFEBS Journal Mutagenesis of hydrogenase accessory genes of Synechocystis sp. PCC 6803 Additional homologues of hypA and hypB are not active in hydrogenase maturation Dorte Hoffmann Kirstin Gutekunst Monika Klissenbauer Rudiger Schulz-Friedrich and Jens Appel Botanisches Institut Christian-Albrechts University Kiel Germany Keywords hyp genes cobalt transport arginase agmatinase cyanobacteria Correspondence J. Appel Botanisches Institut University of Kiel Am Botanischen Garten 1-9 24118 Kiel Germany Fax 49 431 880 4238 Tel 49 431 880 4237 E-mail jappel@bot.uni-kiel.de Received 13 May 2006 revised 27 June 2006 accepted 9 August 2006 doi 10.1111 j.1742-4658.2006.05460.x Genes homologous to hydrogenase accessory genes are scattered over the whole genome in the cyanobacterium Synechocystis sp. PCC 6803. Deletion and insertion mutants of hypAl slr1675 hypBl sll1432 hypC hypD hypE and hypF were constructed and showed no hydrogenase activity. Involvement of the respective genes in maturation of the enzyme was confirmed by complementation. Deletion of the additional homologues hypA2 sll1078 and hypB2 sll1079 had no effect on hydrogenase activity. Thus hypAl and hypBl are specific for hydrogenase maturation. We suggest that hypA2 and hypB2 are involved in a different metal insertion process. The hydrogenase activity of DhypAl and DhypBl could be increased by the addition of nickel suggesting that HypA1 and HypB1 are involved in the insertion of nickel into the active site of the enzyme. The urease activity of all the hypA and hypB single- and double-mutants was the same as in wildtype cells. Therefore there seems to be no common function for these two hyp genes in hydrogenase and urease maturation in Synechocystis. Similarity searches in the whole genome yielded Slr1876 as the best candidate for the hydrogenase-specific protease. The respective deletion mutant had no hydrogenase activity. Deletion of hupE had no effect on hydrogenase activity but resulted in a mutant unable