Parasitology

Research Article

Characterization of monomeric DNA-binding protein Histone H1 in Leishmania braziliensis

EMMA CARMELOa1 c1, GLORIA GONZÁLEZa2, TERESA CRUZa2, ANTONIO OSUNAa2, MARIANO HERNÁNDEZa1 and BASILIO VALLADARESa1

a1 Instituto de Enfermedades Tropicales y Salud Pública de Canarias. Universidad de La Laguna. Av. Astrofisico Fco. Sanchez, s/n. 38202 La Laguna, Tenerife, Spain

a2 Instituto de Biotecnología, Universidad de Granada. Campus Fuentenueva 18071, Granada, Spain

SUMMARY

Histone H1 in Leishmania presents relevant differences compared to higher eukaryote counterparts, such as the lack of a DNA-binding central globular domain. Despite that, it is apparently fully functional since its differential expression levels have been related to changes in chromatin condensation and infectivity, among other features. The localization and the aggregation state of L. braziliensis H1 has been determined by immunolocalization, mass spectrometry, cross-linking and electrophoretic mobility shift assays. Analysis of H1 sequences from the Leishmania Genome Database revealed that our protein is included in a very divergent group of histones H1 that is present only in L. braziliensis. An antibody raised against recombinant L. braziliensis H1 recognized specifically that protein by immunoblot in L. braziliensis extracts, but not in other Leishmania species, a consequence of the sequence divergences observed among Leishmania species. Mass spectrometry analysis and in vitro DNA-binding experiments have also proven that L. braziliensis H1 is monomeric in solution, but oligomerizes upon binding to DNA. Finally, despite the lack of a globular domain, L. braziliensis H1 is able to form complexes with DNA in vitro, with higher affinity for supercoiled compared to linear DNA.

(Received February 15 2011)

(Revised March 30 2011)

(Revised May 03 2011)

(Accepted May 04 2011)

(Online publication July 18 2011)

Correspondence:

c1 Corresponding author: Instituto de Enfermedades Tropicales y Salud Pública de Canarias. Universidad de La Laguna. Av. Astrofisico Fco. Sanchez, s/n. 38202 La Laguna, Tenerife, Spain. Tel: 0034 922316502 ext. 6109. Fax: 0034 922318514. E-mail: ecarmelo@ull.es

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