A PUTATIVE SIGNAL RECOGNITION PARTICLE RECEPTOR A SUBUNIT (SR-ALPHA) HOMOLOG IS EXPRESSED IN THE HYPERTHERMOPHILIC CRENARCHAEON SULFOLOBUS-ACIDOCALDARIUS

A 1.64 kb genomic DNA sequence from the hyperthermophilic crenarchaeon Sulfolobus acidocaldarius is composed of two adjacent genes, The firs t functionally unassigned open reading frame (orf-l) comprises 450 bas e pairs. The second 1.1 kb large open reading frame encodes the putati ve signal recognition particle receptor oc subunit (SR alpha). Both ge nes are expressed under the heterotrophic growth conditions of the org anism. The main transcript of orf-l appears as a monocistronic RNA in Northern hybridization. With regard to SR alpha the transcription patt ern was investigated by reverse transcription polymerase chain reactio n and primer extension analysis. A polyclonal antiserum directed again st E, coli lacZ'/Sulfolobus SR alpha fusion protein detects a 40.5 kDa protein (p41) in agreement with the 41.4 kDa as deduced from the nucl eotide sequence.