Functional characterization of a small heat shock protein from Mycobacterium leprae.
BACKGROUND
Small heat shock proteins are ubiquitous family of stress proteins, having a role in virulence and survival of the pathogen. M. leprae, the causative agent of leprosy is an uncultivable organism in defined media, hence the biology and function of proteins were examined by cloning M. leprae genes in heterologous hosts. The study on sHsp18 was carried out as the knowledge about the functions of this major immunodominant antigen of M. leprae is scanty.


RESULTS
The gene encoding Mycobacterium leprae small heat shock protein (sHsp18) was amplified from biopsy material of leprosy patients, and cloned and expressed in E. coli. The localization and in vitro characterization of the protein are detailed in this report. Data show that major portion of the protein is localized in the outer membrane of E. coli. The purified sHsp18 functions as an efficient chaperone as shown by their ability to prevent thermal inactivation of restriction enzymes SmaI and NdeI. Physical interaction of the chaperone with target protein is also demonstrated. Size exclusion chromatography of purified protein shows that the protein can form multimeric complexes under in vitro conditions as is demonstrated for several small heat shock proteins.


CONCLUSIONS
The small heat shock protein sHsp18 of M. leprae is a chaperone and shows several properties associated with other small heat shock proteins. Membrane association and in vitro chaperone function of sHsp18 shows that the protein may play a role in the virulence and survival of M. leprae in infected host.
Lini
Nirmala
N
Department of Genetic Engineering, School of Biotechnology, Madurai Kamaraj University, Tamil Nadu, India. lininirmala@gmail.com
Rehna
Elengikal Abdul Azeez
EA
Shiburaj
Sugathan
S
Maheshwari
Jayapal Jeya
JJ
Shankernarayan
Nallakandy Panagadan
NP
Dharmalingam
Kuppamuthu
K
D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D050888:Heat-Shock Proteins, Small / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007918:Leprosy / Q000382:microbiology*; D018832:Molecular Chaperones / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D009166:Mycobacterium leprae / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D021381:Protein Transport
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D050888:Heat-Shock Proteins, Small; D018832:Molecular Chaperones