Heat shock response by the hyperthermophilic archaeon Pyrococcus furiosus

Abstract

Collective transcriptional analysis of heat shock response in the hyperthermophilic archaeon Pyrococcus furiosus was examined by using a targeted cDNA microarray in conjunction with Northern analyses. Differential gene expression suggests that P. furiosus relies on a cooperative strategy of rescue (thermosome [Hsp60], small heat shock protein [Hsp20], and two VAT-related chaperones), proteolysis (proteasome), and stabilization (compatible solute formation) to cope with polypeptide processing during thermal stress.

FIG. 1.

(A) Growth curve for P. furiosus grown on tryptone + S⁰ (1% wt/vol) in SSM at 90°C. Cells were subjected to a 60-min heat shock at 105°C during exponential growth. (B) Fluorescence signal intensities of reciprocally labeled cDNA from cells grown at 90°C. (C) Fluorescent signal intensities of heat shock versus unperturbed growth. The upper and lower diagonal lines indicate twofold differential expression.

FIG. 2.

Protein folding in P. furiosus based on differential gene expression of ORFs. Fold values are presented for the heat shock experiment and the biological replicate. P. furiosus appears to utilize primarily Hsp20 and Hsp60 (and possibly VAT) as the major components of the refolding cascade while relying on the proteasome for energy-dependent proteolysis.

FIG. 3.

Northern analysis of selected genes included on the P. furiosus targeted cDNA microarray under conditions of 105°C (A) and 90°C (B). Also shown are genes encoding a putative myo-inositol phosphatase (PF1616) and two transcription factors homologs, TFIIB (PF1377 and PF0687), not included on the array (NI). Fold changes for the biological replicate are shown in parentheses.