Werlang Isabel C R, Schneider Cristopher Z, Mendonça Jordana D, Palma Mario S, Basso Luiz A, Santos Diógenes S
Programa de Pós-Graduação em Biologia Celular e Molecular, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, Porto Alegre, RS 91501-970, Brazil.
Centro de Pesquisas em Biologia Molecular e Funcional, Instituto Nacional de Ciência e Tecnologia em Tuberculose, Pontifícia Universidade Católica do Rio Grande do Sul, Av. Ipiranga 6681, Porto Alegre, RS 90619-900, Brazil.
Microbiology (Reading). 2009 Aug;155(Pt 8):2652-2663. doi: 10.1099/mic.0.030148-0. Epub 2009 May 28.
Tuberculosis remains the major cause of mortality due to a bacterial pathogen, Mycobacterium tuberculosis. The molecular mechanisms of infection and persistence have not been completely elucidated for this pathogen. Studies involving nucleoid-associated proteins (NAPs), which have been related to the control and influence of virulence genes in pathogenic bacteria, can help unveil the virulence process of M. tuberculosis. Here, we describe the initial characterization of an ORF for an M. tuberculosis putative NAP. The Rv3852 gene was cloned and expressed, and its product purified to homogeneity. A qualitative protein-DNA binding assay was carried out by gel-retardation and the protein affinity for specific DNA sequences was assessed quantitatively by surface plasmon resonance (SPR). A stoichiometry of 10 molecules of monomeric protein per molecule of DNA was determined. The monophasic apparent dissociation rate constant values increased to a saturable level as a function of protein concentration, yielding two limiting values for the molecular recognition of proU2 DNA. A protein-DNA binding mechanism is proposed. In addition, functional complementation studies with an Escherichia coli hns mutant reinforce the likelihood that the Rv3852 protein represents a novel NAP in M. tuberculosis.
结核病仍然是由细菌病原体结核分枝杆菌导致死亡的主要原因。该病原体的感染和持续存在的分子机制尚未完全阐明。涉及类核相关蛋白(NAPs)的研究,这些蛋白与病原菌中毒力基因的控制和影响有关,有助于揭示结核分枝杆菌的毒力过程。在此,我们描述了结核分枝杆菌假定NAP的一个开放阅读框(ORF)的初步特征。Rv3852基因被克隆并表达,其产物被纯化至同质。通过凝胶阻滞进行了定性的蛋白质-DNA结合测定,并通过表面等离子体共振(SPR)定量评估了蛋白质对特定DNA序列的亲和力。确定了每分子DNA有10个单体蛋白分子的化学计量比。单相表观解离速率常数的值随着蛋白质浓度的增加而增加至饱和水平,得出了对proU2 DNA分子识别的两个极限值。提出了一种蛋白质-DNA结合机制。此外,用大肠杆菌hns突变体进行的功能互补研究增强了Rv3852蛋白代表结核分枝杆菌中一种新型NAP的可能性。