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The genome sequence of the facultative intracellular pathogen Brucella melitensis
Vito G DelVecchio1, Vinayak Kapatral, Rajendra J Redkar
1Institute of Molecular Biology and Medicine, University of Scranton, Scranton, PA 18510, USA. vimbm@aol.com
Abstract:
Brucella melitensis is a facultative intracellular bacterial pathogen that causes abortion in goats and sheep and Malta fever in humans. The genome of B. melitensis strain 16M was sequenced and found to contain 3,294,935 bp distributed over two circular chromosomes of 2,117,144 bp and 1,177,787 bp encoding 3,197 ORFs. By using the bioinformatics suite ERGO, 2,487 (78%) ORFs were assigned functions. The origins of replication of the two chromosomes are similar to those of other alpha-proteobacteria. Housekeeping genes, including those involved in DNA replication, transcription, translation, core metabolism, and cell wall biosynthesis, are distributed on both chromosomes. Type I, II, and III secretion systems are absent, but genes encoding sec-dependent, sec-independent, and flagella-specific type III, type IV, and type V secretion systems as well as adhesins, invasins, and hemolysins were identified. Several features of the B. melitensis genome are similar to those of the symbiotic Sinorhizobium meliloti.
Insights
Brucella melitensis, a pathogen causing animal abortion and human Malta fever, has a sequenced genome revealing key virulence factors. Its genome structure shares similarities with symbiotic bacteria, offering insights into its pathogenesis.
Area of Science:
- Genomics
- Microbiology
- Pathogen Research
Background:
- Brucella melitensis is a significant bacterial pathogen responsible for zoonotic diseases like Malta fever.
- It causes reproductive losses in livestock, including goats and sheep.
Purpose of the Study:
- To sequence and analyze the genome of Brucella melitensis strain 16M.
- To identify genes and pathways involved in B. melitensis virulence and survival.
Main Methods:
- Whole-genome sequencing of B. melitensis strain 16M.
- Bioinformatic analysis using the ERGO suite to identify Open Reading Frames (ORFs) and assign functions.
- Comparative genomic analysis.
Main Results:
- The B. melitensis 16M genome comprises 3,294,935 bp on two circular chromosomes, encoding 3,197 ORFs.
- 78% of ORFs were assigned functions, with housekeeping genes distributed across both chromosomes.
- Absence of Type I, II, and III secretion systems, but presence of various other secretion systems and virulence factors like adhesins and hemolysins.
- Genomic similarities were observed between B. melitensis and the symbiotic alpha-proteobacterium Sinorhizobium meliloti.
Conclusions:
- The B. melitensis genome contains a repertoire of genes crucial for its intracellular lifestyle and pathogenicity.
- Comparative genomics reveals potential links between pathogenic and symbiotic lifestyles in alpha-proteobacteria.