The Mycobacterium bovis homologous protein of the Mycobacterium tuberculosis serine/threonine protein kinase Mbk (PknD) is truncated

We previously identified a 70-kDa serine/threonine protein kinase (MbK or P knD) from Mycobacterium tuberculosis Erdman containing a transmembrane doma in and bearing a 270-amino acid N-terminal kinase domain. With the use of a polyclonal serum, Mbk has now been identified by Western blotting in prote in extracts from M. tuberculosis and confirmed to be localised in the envel ope. An identical mbk gene has been found by sequencing different M. tuberc ulosis and M. africanum strains. Surprisingly, in two virulent M. bovis str ains and four different strains of M. bovis BCG, an additional adenine afte r position 829 of the open reading frame was found that produces a frame sh ift resulting in a predicted truncated, presumably free cytoplasmic protein , encoding only the N-terminal 30-kDa Mbk kinase domain. This sequence poly morphism has been confirmed by Western blot analysis of M. bovis BCG protei n extracts. (C) 2000 Federation of European Microbiological Societies. Publ ished by Elsevier Science B.V. All rights reserved.