Trypanosoma brucei homologous recombination is dependent on substrate length and homology, though displays a differential dependence on mismatch repair as substrate length decreases

Barnes, R. L. and McCulloch, R. (2007) Trypanosoma brucei homologous recombination is dependent on substrate length and homology, though displays a differential dependence on mismatch repair as substrate length decreases. Nucleic Acids Research, 35(10), pp. 3478-3493. (doi:10.1093/nar/gkm249)

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Publisher's URL: http://dx.doi.org/10.1093/nar/gkm249

Abstract

Homologous recombination functions universally in the maintenance of genome stability through the repair of DNA breaks and in ensuring the completion of replication. In some organisms, homologous recombination can perform more specific functions. One example of this is in antigenic variation, a widely conserved mechanism for the evasion of host immunity. <i>Trypanosoma brucei</i>, the causative agent of sleeping sickness in Africa, undergoes antigenic variation by periodic changes in its variant surface glycoprotein (VSG) coat. VSG switches involve the activation of VSG genes, from an enormous silent archive, by recombination into specialized expression sites. These reactions involve homologous recombination, though they are characterized by an unusually high rate of switching and by atypical substrate requirements. Here, we have examined the substrate parameters of T. brucei homologous recombination. We show, first, that the reaction is strictly dependent on substrate length and that it is impeded by base mismatches, features shared by homologous recombination in all organisms characterized. Second, we identify a pathway of homologous recombination that acts preferentially on short substrates and is impeded to a lesser extent by base mismatches and the mismatch repair machinery. Finally, we show that mismatches during T. brucei recombination may be repaired by short-patch mismatch repair.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:McCulloch, Professor Richard
Authors: Barnes, R. L., and McCulloch, R.
Subjects:Q Science > QH Natural history > QH345 Biochemistry
College/School:College of Medical Veterinary and Life Sciences
College of Medical Veterinary and Life Sciences > Institute of Infection Immunity and Inflammation
College of Medical Veterinary and Life Sciences > Institute of Molecular Cell and Systems Biology
Journal Name:Nucleic Acids Research
Publisher:Oxford University Press
ISSN:0305-1048
ISSN (Online):1362-4962
Published Online:03 May 2007
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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
401101DNA recombination pathways and antigenic variation in trypanosoma bruceiRichard McCullochMedical Research Council (MRC)G0401553Infection Immunity and Inflammation Life Sciences