A protein-based phylogenetic tree for Gram-positive bacteria derived from hrcA, a unique heat-shock regulatory gene

Citation
S. Ahmad et al., A protein-based phylogenetic tree for Gram-positive bacteria derived from hrcA, a unique heat-shock regulatory gene, INT J SY B, 49, 1999, pp. 1387-1394
Citations number
43
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Microbiology
Journal title
INTERNATIONAL JOURNAL OF SYSTEMATIC BACTERIOLOGY
ISSN journal
0020-7713 → ACNP
Volume
49
Year of publication
1999
Part
4
Pages
1387 - 1394
Database
ISI
SICI code
0020-7713(199910)49:<1387:APPTFG>2.0.ZU;2-E
Abstract
The dnaK operon from Bacillus subtilis and other Cram-positive bacteria wit h low G+C DNA content contains additional heat-shock genes, including hrcA. The hrcA gene encodes a transcription factor that negatively regulates hea t-shock genes and is uniformly present in all Cram-positive bacteria studie d to date. An hrcA homologue is also present in Synechocystis species, Lept ospira interrogans, Chlamydia trachomatis, Caulobacter crescentus and Metha nococcus jannaschii, organisms that diverged early on from the common ances tor of all Gram-positive bacteria and Proteobacteria, according to 16S rRNA phylogeny. A partial, protein-based phylogenetic tree, derived using amino acid sequence homology of hrcA proteins from Cram-positive bacteria, is pr esented here, and the results are compared with the phylogenetic trees gene rated from 16S rRNA, dnaK and dnaJ sequences. The location of the hrcA gene and the genome organization of the dnaK operon support the division of all Gram-positive bacteria into three major groups: one group contains high-GC Gram-positive bacteria, and two others contain low-G+C Gram-positive bact eria. Among the Gram-positive bacteria with low G+C DNA content, the result s indicate that there is a close phylogenetic relationship between Bacillus species and Clostridium species on the one hand and between Lactococcus la ctis and Streptococcus mutans on the other. Streptomyces and Mycobacterium species also exhibited a close relationship. A hierarchical arrangement of Gram-positive bacteria based on HrcA sequences is proposed as an additional refinement of the phylogenetic relationships within this important bacteri al group.