The Mycobacterium avium-intracellulare Complex dnaB Locus and Protein Intein Splicing

• Published in: Biochemical and biophysical research communications Vol. 280; no. 3; pp. 898 - 903
• Main Authors: Yamamoto, Kohji, Low, Brad, Rutherford, Stacey A., Rajagopalan, Malini, Madiraju, Murty V.V.S.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 26-01-2001
• Subjects: Bacterial Proteins; Base Sequence; DNA Helicases - chemistry; DNA Helicases - genetics; DNA Helicases - metabolism; DNA Primers - genetics; DnaB; DnaB Helicases; Genes, Bacterial; inteins; mutagenesis; mycobacteria; Mycobacterium avium Complex - genetics; Mycobacterium avium Complex - metabolism; mycobacterium-intracellulare complex; PCR; Protein Precursors - chemistry; Protein Precursors - genetics; Protein Precursors - metabolism; Protein Splicing; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; mycobacterium-intracellulare complex; protein splicing; DnaB; mycobacteria; inteins; mutagenesis; PCR
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1006/bbrc.2000.4202

Intein is a protein sequence mebedded in-frame within a precursor protein and is posttranslationally excised by a self-catalytic protein splicing process. Protein splicing is believed to follow a pathway requiring Cys, Ser, or Thr residues at the intein N-terminus and substitutions other than Cys, Ser, or Thr residues prevent splicing. We show that the dnaB locus in some strains of M. avium-intracellulare complex (MAC) contains intein and that the intein N-terminal amino acid is Ala [Ala-type]. We demonstrate that the M. avium DnaB precursor protein undergoes posttranslational proteolytic processing producing proteins corresponding to the sizes of the DnaB and intein. Further, by Western analysis we detect a protein corresponding to the size of the spliced DnaB protein in MAC cell extracts. Together, these results indicate that the Ala-type MAC DnaB inteins can splice and provide another example that points to an interesting alternative splicing mechanism (Southworth, M. W., Benner, J., and Perler, F. B., EMBO J. 19, 5019–5026, 2000).