A transcriptome study was performed onSulfolobus islandicusREY15A actively undergoing CRISPR spacer acquisition from the crenarchaeal monocaudavirus STSV2 in rich and basal media over a 6 day period. Spacer acquisition preceded strong host growth retardation, altered transcriptional activity of four different CRISPR-Cas modules and changes in viral copy numbers, and with significant differences in the two media. Transcript levels of proteins involved in the cell cycle were reduced, whereas those of DNA replication, DNA repair, transcriptional regulation and some antitoxin–toxin pairs and transposases were unchanged or enhanced. Antisense RNAs were implicated in the transcriptional regulation of adaptation and interference modules of the type I-A CRISPR-Cas system, and evidence was found for the occurrence of functional co-ordination between the single CRISPR-Cas adaptation module and the functionally diverse interference modules.
CRISPR-Cas is an archaeal and bacterial adaptive immune system which generates memory from viral infections. Different functional modules coordinate their responses and ultimately reduce or eliminate invading viruses utilising the acquired memory. We describe the virus-host interaction of STSV2 with its crenarchaeal Sulfolobus host during CRISPR-Cas responses which produce growth arrest and CRISPR spacer acquisition over several days. Viral propagation was positively enhanced by increased nutrient availability but was counteracted by enhanced CRISPR memory generation in the host.