CRISPR-associated Proteins

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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

Cas-Protein aa sequences

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.

Usually found usually in the order cas3-cas4-cas1-cas2.

Huzzah! Our genome's Cas-proteins appear in the same order! (Well....2-1-4-3...but still!)

"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]."SSO1450 – A CAS1 protein from Sulfolobus solfataricus P2 with high affinity for RNA and DNA