title: CRISPR families of the crenarchaeal genus Sulfolobus: bidirectional transcription and dynamic properties.
abstract: Clusters of regularly interspaced short palindromic repeats (CRISPRs) of Sulfolobus fall into three main families based on their repeats, leader regions, associated cas genes and putative recognition sequences on viruses and plasmids. Spacer sequence matches to different viruses and plasmids of the Sulfolobales revealed some bias particularly for family III CRISPRs. Transcription occurs on both strands of the five repeat-clusters of Sulfolobus acidocaldarius and a repeat-cluster of the conjugative plasmid pKEF9. Leader strand transcripts cover whole repeat-clusters and are processed mainly from the 3'-end, within repeats, yielding heterogeneous 40-45 nt spacer RNAs. Processing of the pKEF9 leader transcript occurred partially in spacers, and was incomplete, probably reflecting defective repeat recognition by host enzymes. A similar level of transcripts was generated from complementary strands of each chromosomal repeat-cluster and they were processed to yield discrete approximately 55 nt spacer RNAs. Analysis of the partially identical repeat-clusters of Sulfolobus solfataricus strains P1 and P2 revealed that spacer-repeat units are added upstream only when a leader and certain cas genes are linked. Downstream ends of the repeat-clusters are conserved such that deletions and recombination events occur internally.
authors.affiliation: Centre for Comparative Genomics, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen N, Denmark.
authors.forename: Reidun K
authors.initials: RK
authors.lastname: Lillestøl
authors.forename: Shiraz A
authors.initials: SA
authors.lastname: Shah
authors.forename: Kim
authors.initials: K
authors.lastname: Brügger
authors.forename: Peter
authors.initials: P
authors.lastname: Redder
authors.forename: Hien
authors.initials: H
authors.lastname: Phan
authors.forename: Jan
authors.initials: J
authors.lastname: Christiansen
authors.forename: Roger A
authors.initials: RA
authors.lastname: Garrett
mesh_terms: D020121:5' Untranslated Regions; D055029:Inverted Repeat Sequences; D005810:Multigene Family; D010802:Phylogeny; D019642:RNA, Archaeal / Q000235:genetics; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D016944:Sulfolobus / Q000235:genetics*; D024363:Transcription Initiation Site; D014158:Transcription, Genetic
chemical_list: D020121:5' Untranslated Regions; D019642:RNA, Archaeal