Louw Cassandra A, Ludewig Michael H, Blatch Gregory L
Biomedical Biotechnology Research Unit, Department of Biochemistry, Microbiology and Biotechnology, Rhodes University, Grahamstown 6140, South Africa.
Protein Expr Purif. 2010 Feb;69(2):168-77. doi: 10.1016/j.pep.2009.09.023. Epub 2009 Oct 6.
The heat shock protein 40 (Hsp40) family of proteins act as co-chaperones of the heat shock protein 70 (Hsp70) chaperone family, and together they play a vital role in the maintenance of cellular homeostasis. The Type III class of Hsp40s are diverse in terms of both sequence identity and function and have not been extensively characterised. The Trypanosoma brucei parasite is the causative agent of Human African Trypanosomiasis, and possesses an unusually large Hsp40 complement, consisting mostly of Type III Hsp40s. A novel T. brucei Type III Hsp40, Tbj1, was heterologously expressed, purified, and found to exist as a compact monomer in solution. Using polyclonal antibodies to the full-length recombinant protein, Tbj1 was found by Western analysis to be expressed in the T. brucei bloodstream-form. Tbj1 was found to be able to assist two different Hsp70 proteins in the suppression of protein aggregation in vitro, despite being unable to stimulate their ATPase activity. This indicated that while Tbj1 did not possess independent chaperone activity, it potentially functioned as a novel co-chaperone of Hsp70 in T. brucei.
热休克蛋白40（Hsp40）家族蛋白作为热休克蛋白70（Hsp70）伴侣家族的共伴侣，它们共同在维持细胞内稳态中发挥着至关重要的作用。III型Hsp40在序列同一性和功能方面都具有多样性，尚未得到广泛的表征。布氏锥虫是人类非洲锥虫病的病原体，拥有异常庞大的Hsp40补体，主要由III型Hsp40组成。一种新的布氏锥虫III型Hsp40，即Tbj1，被异源表达、纯化，并发现其在溶液中以紧密单体形式存在。使用针对全长重组蛋白的多克隆抗体，通过蛋白质印迹分析发现Tbj1在布氏锥虫血流形式中表达。尽管Tbj1不能刺激两种不同的Hsp70蛋白的ATP酶活性，但发现它能够在体外协助这两种Hsp70蛋白抑制蛋白质聚集。这表明，虽然Tbj1不具有独立的伴侣活性，但它可能在布氏锥虫中作为Hsp70的一种新型共伴侣发挥作用。
