Regulation of the Aspergillus nidulans Pectate Lyase Gene (pelA)

Abstract

Aspergillus nidulans pectate lyase was purified from culture filtrates. The enzyme catalyzed a random eliminative cleavage reaction, had an apparent molecular weight of 40,000, and a pl of 4.2. Pectate lyase antisera were produced and used to identify pectate lyase clones in a cDNA expression library. Thirteen of 14 clones identified immunologically cross-hybridized. The identity of the single-copy pectate lyase gene, which we designated pelA, was confirmed in two ways. First, several cDNA clones expressed pectate lyase activity in Escherichia coil. Second, targeted mutation of the gene in A. nidulans resulted in complete loss of enzyme activity, pelA encodes a 1,300-nucleotide mRNA that was present in cells grown with polygalacturonic acid as carbon source but absent from cells grown with glucose or acetate as carbon source. Thus, pectate lyase expression is regulated at the level of mRNA accumulation.

Isolation and characterization of polygalacturonase genes (pecA and pecB) from Aspergillus flavus

“…The medium contained either pectin at 0.5% or other carbon sources at 1%. Mycelia were grown in glucose medium for 15 h before being shifted to glucose, pectin, pectin and glucose, or mannitol for 5 h prior to harvest for RNA extraction (17). All carbon sources were purchased from Sigma Chemical Company (St. Louis, Mo.…”

Production of Cell Wall-Degrading Enzymes by Aspergillus nidulans: A Model System for Fungal Pathogenesis of Plants

“…Interestingly, the catabolite derepression mutation creA204 does not relieve repression of these enzymes. In the accompanying paper (Dean and Timberlake, 1989), we report isolation, characterization, and inactivation of the single copy A. nidulans pectate lyase gene (pelA).…”

The polygalacturonases of Aspergillus niger are encoded by a family of diverged genes

“…For example, in A . nidulans a mutation in the creA gene that is involved in carbon-catabolite repression resulted in pectate-lyase-mRNA overproduction by cells grown in medium containing polygalacturonic acid as sole carbon source, but did not relieve carbon-catabolite repression by glucose [8]. Genetic evidence for the requirement of an inducer molecule and for concerted regulation of polygalacturonase and pectinlyase genes comes from a Verticillium albo-atrum mutant which was unable to utilize galacturonides and was therefore deficient in production of inducible polygalacturonase as well as pectin-lyase [I 61.…”

“…Polygalacturonases as well as other pectolytic enzymes are produced by many organisms (reviewed in [2]), and microbial pectolytic enzymes have been extensively studied in relation to plant pathogenesis. The molecular biology of the bacterial enzymes, especially the pectate lyases of Erwiniu, is well developed compared to that of the pectolytic enzymes of fungal pathogens [3, 41. Recently, genomic or cDNA clones coding for pectinesterase [5], pectin lyases [6, 71, pectate lyase [8] and polygalacturonases [9 -121 have been obtained from Aspei-gillus species, which are considered to be saprophytes. The availability of commercial pectinase preparations derived from Aspergillus niger has contributed to the rapid progress in gene Correspondence to J. Visser, Section of Molccular Genetics, Department of Genetics, Wageningen Agricultural University, Dreyenlaan Note.…”