Open AccessCharacterization of the minimal replicon of p HM 300 and independent copy number control of major and minor chromosomes of H aloferax mediterranei
Author(s) -
Liu Xiaoqing,
Miao Di,
Zhang Fan,
Wu Zhenfang,
Liu Jingfang,
Xiang Hua
Publication year - 2013
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/1574-6968.12052
Subject(s) - replicon , biology , genetics , minichromosome , chromosome , origin of replication , gene , dna replication , plasmid
The presence of minichromosomes is very common in haloarchaea, but little is known about the coordination of replication between the major and minor chromosomes. In this study, we analyzed the replication of p HM 300, a 321,908‐bp minichromosome, which encodes versatile metabolism pathways in H aloferax mediterranei . The replication origin of p HM 300 was predicted in the 699‐bp intergenic region between the cdc6K and tbp4 gene, and the minimal replicon, consisting of an AT‐rich region flanked by putative origin recognition boxes ( ORB s) and the adjacent cdc6K gene, was determined by assaying for its ability to replicate autonomously in H aloarcula hispanica . Southern blot analysis indicated that the ratio of p HM 300 to chromosome increased from the early exponential to middle stationary phase. The copy numbers of these minor and major chromosomes were then evaluated by real‐time PCR and showed that both decreased in stationary phase. However, the decrease in the copy number of the major chromosome was a little earlier and much greater than that of p HM 300, revealing that the copy number control of the minichromosome p HM 300 is independent from that of the major chromosome in H . mediterranei .