Comparison and correlation of Simple Sequence Repeats distribution in genomes of Brucella species.

Somesula Swapna Rekha,Srinivasan Shanthi Kruti,Matcha Bhaskar,Jangampalli Adi Pradeep Kiran,Yellapu Nanda Kumar,Veeraraghavulu Praveen Chakravarthi

doi:10.6026/97320630006179

Abstract

Computational genomics is one of the important tools to understand the distribution of closely related genomes including simple sequence repeats (SSRs) in an organism, which gives valuable information regarding genetic variations. The central objective of the present study was to screen the SSRs distributed in coding and non-coding regions among different human Brucella species which are involved in a range of pathological disorders. Computational analysis of the SSRs in the Brucella indicates few deviations from expected random models. Statistical analysis also reveals that tri-nucleotide SSRs are overrepresented and tetranucleotide SSRs underrepresented in Brucella genomes. From the data, it can be suggested that over expressed tri-nucleotide SSRs in genomic and coding regions might be responsible in the generation of functional variation of proteins expressed which in turn may lead to different pathogenicity, virulence determinants, stress response genes, transcription regulators and host adaptation proteins of Brucella genomes. SSRs - Simple Sequence Repeats, ORFs - Open Reading Frames.

Highlights

Brucellosis is one of the bacterial zoonoses caused by organisms belonging to the genus Brucella, gram-negative, non-spore-forming, facultative, intracellular bacteria
Considering the facts that a) Brucella species viz., B. melitensis 16M, B. suis, B. abortusS19 and B. canisATCC23365, are involved in many hazardous health effects in humans [1], b) these species share DNA sequences of about 90% similarities [2] c) SSRs are primarily involved in virulence and pathogenic nature of bacteria [5] and d) studies related to distribution pattern of SSRs are little exploited in Brucella species, the present study was an attempt to ISSN 0973-2063 0973-8894
0.63, 0.59, 0.52 and 0.51 of Brucella abortusS19, Brucella suis, Brucella canis ATCC23365 and Brucella melitensis16M respectively in the genomic regions (Figure 1) On contrary, the tri-nucleotide SSRs showed a distinct variability with extensive level of overrepresentation in both genomic and coding regions of four Brucella species with mean values of 1.46, 1.53, 1.20, 2.06.and 2.07, 2.43, 1.82, 3.39.while in tetra-nucleotide SSRs showed under representation with mean values of 0.25, 0.28, 0.14, 0.17 in genomic and 0.19, 0.22, 0.09, 0.06 and coding region

Summary

Introduction

Brucellosis is one of the bacterial zoonoses caused by organisms belonging to the genus Brucella, gram-negative, non-spore-forming, facultative, intracellular bacteria. The primary cause of microsatellite polymorphism is thought to be strand slippage during DNA replication [16] These microsatellites provide a framework for crucial genetic rearrangements with their reversible frame-shift mutations that can confer a certain degree of selective advantage of pathogenic bacteria. These microsatellites act as gene regulators, the loss or gain of repeats in the promoter region can regulate transcriptional activity [17]. Considering the facts that a) Brucella species viz., B. melitensis 16M, B. suis, B. abortusS19 and B. canisATCC23365, are involved in many hazardous health effects in humans [1], b) these species share DNA sequences of about 90% similarities [2] c) SSRs are primarily involved in virulence and pathogenic nature of bacteria [5] and d) studies related to distribution pattern of SSRs are little exploited in Brucella species, the present study was an attempt to ISSN 0973-2063 (online) 0973-8894 (print)

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Discussion

Conclusion