[A putative NtcA-regulating gene, alr1390, in Anabaena sp. PCC 7120].

UNLABELLED

NtcA is a master transcriptional regulator in global nitrogen control in Anabaena. Heterocyst differentiation depends on the NtcA protein. A large number of genes regulated by NtcA have a consensus sequence, GTA-N8-TAC, for NtcA binding. Bioinformatics analysis of alr1390 in the chromosome of Anabaena sp. PCC 7120 indicates that there is a conservative NtcA binding box, GTA-TAGTTTTC-TAC, upstream the putative tsp position of alr1390.

OBJECTIVE

To understand the relationship between alr1390 and NtcA, METHODS: Real-time RT-PCR and EMSA were used.

RESULTS

Real-time RT-PCR results showed that the transcriptional level of alr1390 remained constant before and after combined nitrogen step-down in wild type Anabaena sp. PCC 7120. However, in the ntcA mutant, there was an increase in the transcriptional level of alr1390 after 12h of combined nitrogen step-down, which indicated that alr1390 should be subject to the regulation of NtcA. Additionally although no conspicuous NtcA-alr1390 complex was detected by EMSA in vitro, a smear appeared in gel electrophoresis.

CONCLUSION

These results suggested that alr1390 might be regulated by NtcA.