Dual nuclease activity of a Cas2 protein in CRISPR–Cas subtype I‐B of Leptospira interrogans

• Published in: FEBS letters 2016-04, Vol.590 (7), p.1002-1016
• Main Authors: Dixit, Bhuvan, Ghosh, Karukriti Kaushik, Fernandes, Gary, Kumar, Pankaj, Gogoi, Prerana, Kumar, Manish
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Amino Acid Substitution; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Cas protein; Computational Biology; CRISPR-Cas Systems; CRISPR–Cas; Databases, Protein; DNA, Single-Stranded - metabolism; DNA, Viral - metabolism; Endonucleases - chemistry; Endonucleases - genetics; Endonucleases - metabolism; Escherichia coli - enzymology; Escherichia coli - metabolism; Expert Systems; Isoenzymes - chemistry; Isoenzymes - genetics; Isoenzymes - metabolism; Leptospira; Leptospira interrogans - chemistry; Leptospira interrogans - enzymology; Leptospira interrogans - metabolism; Models, Molecular; Molecular Sequence Data; nucleases; Phylogeny; Point Mutation; Protein Conformation; Recombinant Proteins - chemistry; Recombinant Proteins - metabolism; RNA, Bacterial - metabolism; RNase; Sequence Alignment; Substrate Specificity
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1002/1873-3468.12124

Leptospira interrogans serovar Copenhageni strain Fiocruz L1–130 carries a set of cas genes associated with CRISPR–Cas subtype I‐B. Herein, we report for the first time active transcription of a set of cas genes (cas1 to cas8) of L. interrogans where cas4, cas1, cas2 and cas6, cas3, cas8, cas7, cas5 are clustered together in two independent operons. As an initial step toward comprehensive understanding of CRISPR–Cas system in spirochete, the biochemical study of one of the core Leptospira Cas2 proteins (Lep_Cas2) showed nuclease activity on both DNA and RNA in a nonspecific manner. Additionally, unlike other known Cas2 proteins, Lep_Cas2 showed metal‐independent RNase activity and preferential activity on RNA over DNA. These results provide insight for understanding Cas2 diversity existing in the prokaryotic adaptive immune system. Transcription of all the cas genes of CRISPR–Cas subtype I‐B in Leptospira interrogans. First to examine the function of a Cas2 protein in spirochete. RNase activity of Cas2 protein is divalent metal‐independent.