ANALYSIS OF 43 KB OF THE CHLORELLA VIRUS PBCV-1 330-KB GENOME - MAP POSITIONS 45 TO 88

Forty-three kb of DNA, located at the left end (45 to 88 kb) of the 33 0-kb Chlorella virus PBCV-1 genome, was sequenced and analyzed. Eighty -six open reading frames (ORFs) 65 codons or longer ware identified; 4 7 were classified as major ORFs. These 47 major ORFs are densely packe d on both strands of PBCV-1 DNA Seventeen of these major ORFs resemble genes in the sequence databases, including three putative gene produc ts involved in manipulating sugars (glucosamine synthetase, GDP-D-mann ose dehydratase, and N-acetylglucosaminyltransferase), two transcripti on factors, beta-1,3-glucanase, aspartate transcarbamylase, ubiquitin carboxy terminal hydrolase, RNA guanyl transferase, an exonuclease, an d a helicase. This is the first time some of these putative PBCV-1 gen es have been found in a virus genome. One of the transcription factor- like genes contains a type IB self-splicing intron. Since a spliceosom al processed intron was reported previously in the PBCV-1 DNA polymera se gene, PBCV-1 is the first virus known to contain two different type s of introns. (C) 1995 Academic Press, Inc.