Nitrogen-regulated genes for the metabolism of cyanophycin, a bacterial nitrogen reserve polymer -: Expression and mutational analysis of two cyanophycin synthetase and cyanophycinase gene clusters in the heterocyst-forming cyanobacterium Anabaena sp PCC 7120

被引:54
作者
Picossi, S [1 ]
Valladares, A [1 ]
Flores, E [1 ]
Herrero, A [1 ]
机构
[1] Univ Seville, CSIC, Inst Bioquim Vegetal & Fotosintesis, E-41092 Seville, Spain
关键词
D O I
10.1074/jbc.M311518200
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Two gene clusters each encoding the cyanophycin-metabolism enzymes cyanophycin synthetase and cyanophycinase are found in the heterocyst-forming cyanobacterium Anabaena sp. PCC 7120. In cluster cph1, the genes cphB1 and cphA1 were expressed in media containing ammonium, nitrate, or N-2 as nitrogen sources, but expression was higher in the absence of combined nitrogen taking place both in vegetative cells and heterocysts. Both genes were cotranscribed from three putative promoters located upstream of cphB1, and, additionally, the cphA1 gene was expressed monocistronically from at least two promoters located in the intergenic cphB1-cphA1 region. Both constitutive promoters and promoters dependent on the global nitrogen control transcriptional regulator NtcA were identified. In cluster cph2, the cphB2 and cphA2 genes, which are found in opposite orientations, were expressed as monocistronic messages in media containing ammonium, nitrate, or N-2, but expression was higher in the absence of ammonium. Expression of the cph2 genes was lower than that of cph1 genes. Analysis of cph gene insertional mutants indicated that cluster cph1 genes contributed more than cluster cph2 genes to cyanophycin accumulation in the whole filament as well as in heterocysts. Diazotrophic growth was more severely impaired in cyanophycinase than in cyanophycin synthetase mutants, indicating that cyanophycin, although normally synthesized in the heterocysts, is not required for heterocyst function and that the inability to degrade this polymer is detrimental for the diazotrophic growth of the cyanobacterium.
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页码:11582 / 11592
页数:11
相关论文
共 40 条
[1]   CYANOBACTERIAL CELL INCLUSIONS [J].
ALLEN, MM .
ANNUAL REVIEW OF MICROBIOLOGY, 1984, 38 :1-25
[2]  
Ausubel FM, 2003, CURRENT PROTOCOLS MO
[3]   SPATIAL EXPRESSION AND AUTOREGULATION OF HETR, A GENE INVOLVED IN THE CONTROL OF HETEROCYST DEVELOPMENT IN ANABAENA [J].
BLACK, TA ;
CAI, YP ;
WOLK, CP .
MOLECULAR MICROBIOLOGY, 1993, 9 (01) :77-84
[4]   Transcription activation by catabolite activator protein (CAP) [J].
Busby, S ;
Ebright, RH .
JOURNAL OF MOLECULAR BIOLOGY, 1999, 293 (02) :199-213
[5]   USE OF A CONDITIONALLY LETHAL GENE IN ANABAENA SP-STRAIN PCC-7120 TO SELECT FOR DOUBLE RECOMBINANTS AND TO ENTRAP INSERTION SEQUENCES [J].
CAI, YP ;
WOLK, CP .
JOURNAL OF BACTERIOLOGY, 1990, 172 (06) :3138-3145
[6]   Reduction of conjugal transfer efficiency by three restriction activities of Anabaena sp. strain PCC 7120 [J].
ElhaI, J ;
Vepritskiy, A ;
MuroPastor, AM ;
Flores, E ;
Wolk, CP .
JOURNAL OF BACTERIOLOGY, 1997, 179 (06) :1998-2005
[7]  
ELHAI J, 1988, METHOD ENZYMOL, V167, P747
[8]   A VERSATILE CLASS OF POSITIVE-SELECTION VECTORS BASED ON THE NONVIABILITY OF PALINDROME-CONTAINING PLASMIDS THAT ALLOWS CLONING INTO LONG POLYLINKERS [J].
ELHAI, J ;
WOLK, CP .
GENE, 1988, 68 (01) :119-138
[9]   CONDUCTION OF PEC22, A PLASMID CODING FOR MR-CENTER-DOT-ECOT22I, MEDIATED BY A RESIDENT TN3-LIKE TRANSPOSON, TN5396 [J].
ELHAI, J ;
CAI, YP ;
WOLK, CP .
JOURNAL OF BACTERIOLOGY, 1994, 176 (16) :5059-5067
[10]  
Flores E., 1994, The Molecular Biology of Cyanobacteria, P487