title: Identification of a copper-binding metallothionein in pathogenic mycobacteria.
abstract: A screen of a genomic library from Mycobacterium tuberculosis (Mtb) identified a small, unannotated open reading frame (MT0196) that encodes a 4.9-kDa, cysteine-rich protein. Despite extensive nucleotide divergence, the amino acid sequence is highly conserved among mycobacteria that are pathogenic in vertebrate hosts. We synthesized the protein and found that it preferentially binds up to six Cu(I) ions in a solvent-shielded core. Copper, cadmium and compounds that generate nitric oxide or superoxide induced the gene's expression in Mtb up to 1,000-fold above normal expression. The native protein bound copper within Mtb and partially protected Mtb from copper toxicity. We propose that the product of the MT0196 gene be named mycobacterial metallothionein (MymT). To our knowledge, MymT is the first metallothionein of a Gram-positive bacterium with a demonstrated function.
authors: Department of Microbiology and Immunology, Weill Cornell Medical College, 1300 York Avenue, New York, New York 10065, USA.
authors: Ben
authors: B
authors: Gold
authors: Haiteng
authors: H
authors: Deng
authors: Ruslana
authors: R
authors: Bryk
authors: Diana
authors: D
authors: Vargas
authors: David
authors: D
authors: Eliezer
authors: Julia
authors: J
authors: Roberts
authors: Xiuju
authors: X
authors: Jiang
authors: Carl
authors: C
authors: Nathan
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D003001:Cloning, Molecular; D003300:Copper / Q000737:chemistry*; D015964:Gene Expression Regulation, Bacterial; D008668:Metallothionein / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D009169:Mycobacterium tuberculosis / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D016415:Sequence Alignment
chemical_list: D003300:Copper; D008668:Metallothionein