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Updated: Feb 18, 2026
DNA Fingerprinting of Mycobacterium leprae Strains Using Variable Number Tandem Repeat VNTR - Fragment Length Analysis FLA
Published on: July 15, 2011
Sequence homology and expression profile of genes associated with DNA repair pathways in Mycobacterium leprae
Mukul Sharma1, Sundeep Chaitanya Vedithi2, Madhusmita Das3
1Department of Biotechnology, Indian Institute of Technology, Hyderabad, Telangana, India.
Background:
Survival of Mycobacterium leprae, the causative bacteria for leprosy, in the human host is dependent to an extent on the ways in which its genome integrity is retained. DNA repair mechanisms protect bacterial DNA from damage induced by various stress factors. The current study is aimed at understanding the sequence and functional annotation of DNA repair genes in M. leprae.
Methods:
T he genome of M. leprae was annotated using sequence alignment tools to identify DNA repair genes that have homologs in Mycobacterium tuberculosis and Escherichia coli. A set of 96 genes known to be involved in DNA repair mechanisms in E. coli and Mycobacteriaceae were chosen as a reference. Among these, 61 were identified in M. leprae based on sequence similarity and domain architecture. The 61 were classified into 36 characterized gene products (59%), 11 hypothetical proteins (18%), and 14 pseudogenes (23%). All these genes have homologs in M. tuberculosis and 49 (80.32%) in E. coli. A set of 12 genes which are absent in E. coli were present in M. leprae and in Mycobacteriaceae. These 61 genes were further investigated for their expression profiles in the whole transcriptome microarray data of M. leprae which was obtained from the signal intensities of 60bp probes, tiling the entire genome with 10bp overlaps.
Results:
It was noted that transcripts corresponding to all the 61 genes were identified in the transcriptome data with varying expression levels ranging from 0.18 to 2.47 fold (normalized with 16SrRNA). The mRNA expression levels of a representative set of seven genes ( four annotated and three hypothetical protein coding genes) were analyzed using quantitative Polymerase Chain Reaction (qPCR) assays with RNA extracted from skin biopsies of 10 newly diagnosed, untreated leprosy cases. It was noted that RNA expression levels were higher for genes involved in homologous recombination whereas the genes with a low level of expression are involved in the direct repair pathway.
Conclusion:
This study provided preliminary information on the potential DNA repair pathways that are extant in M. leprae and the associated genes.
Insights
This study identifies 61 DNA repair genes in Mycobacterium leprae, crucial for retaining genome integrity and survival in the human host. Gene expression analysis reveals higher levels for homologous recombination pathways, indicating their importance in leprosy.
Area of Science:
- Microbiology
- Genomics
- Molecular Biology
Background:
- Leprosy, caused by Mycobacterium leprae, relies on bacterial genome integrity for host survival.
- DNA repair mechanisms are vital for protecting bacterial DNA from various stress factors.
Purpose of the Study:
- To identify and functionally annotate DNA repair genes in Mycobacterium leprae.
- To understand the role of these genes in maintaining bacterial genome integrity.
Main Methods:
- Genome annotation using sequence alignment tools to identify DNA repair genes.
- Comparative analysis with Mycobacterium tuberculosis and Escherichia coli.
- Transcriptome microarray and quantitative Polymerase Chain Reaction (qPCR) for gene expression profiling.
Main Results:
- 61 DNA repair genes identified in M. leprae, with homologs in M. tuberculosis and E. coli.
- All identified genes showed varying expression levels in transcriptome data.
- Genes involved in homologous recombination exhibited higher expression, while direct repair pathway genes showed lower expression.
Conclusions:
- This study provides foundational insights into the DNA repair pathways present in M. leprae.
- The identified genes and their expression patterns offer potential targets for understanding leprosy pathogenesis.
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