CRISPR-associated Proteins

RAST and JGI agree that our genome has 6 CRISPR-associated (cas) proteins:

1) Cas1

2) Cas2

3) Cas3(helicase)

4) Cas4a (RecB family exonuclease)

5) TM1800 family

6) TM1801 family

After comparing the conserved proteins between our genome and the other 9 genomes, I found these cas-proteins were conserved:

H. sinaiiensis shares all 6 cas-proteins with H. mukohataei.

H. vallismortis shares all cas-proteins except for Cas4.

H. californiae shares all cas-proteins except for Cas4.

H. denitrificans shares all 6 cas-proteins with H. mukohataei.

H. mediteranei shares all 6 cas-proteins with H. mukohataei.

H. volcanii shares only Cas2, Cas3 and Cas4 with H. mukohataei.

H. sulfurifontis shares only Cas1, Cas3 and TM1800.

H. mucosum shares all 6 cas-proteins with H. mukohataei.

H. utahensis shares all 6 cas-proteins with H. mukohataei.

Research:

Several papers agree that Cas1 in particular is highly conserved across genomes. Only H. volcanii does not share the Cas1 gene with the other 9 genomes.

"CRISPR sequences have been found to be flanked by protein genes named cas (CRISPR-associated) genes and their encoded proteins are therefore called CAS proteins [2]. They are typically organized in small clusters and are associated with specific subtypes of CRISPRs. The number of cas genes associated with CRISPR subtypes is also variable, ranging from 6 to more than 20. The specific domains of CAS proteins have been predicted to harbor nuclease, helicase, recombinase, integrase and RNA and/or DNA binding activities [6] and [7]."[1]