The nucleotide sequence of pnl gene encoding pectin lyase (PNL; EC4.2.2.10)from Erwinia carotovora Er was determined. The structural gene of pnl consisted of 942 base pairs. An open reading frame that could encode a 33,700 dalton polypeptide consisting 314 amino acids was assigned. The molecular size of the polypeptide predicted from the amino acid composition was close to the value of PNL determined in E.carotovora Er. The nucleotide sequence of the 5'-flanking region showed the presence of the consensus sequence of ribosome binding site, Pribnow box and the RNA polymerase recognition site in E.carotovora and Escherichia coli. Between the presumed Pribnow box and the ribosome binding site, two pairs of inverted repeats were found. By comparing the predicted amino acid sequences of pnl, several reported bacterial pectate lyases and Aspergillus niger pectin lyase, short regions of homology were found despite the different substrate specificities of these enzymes.