The transport of phenylacetic acid across the peroxisomal membrane is mediated by the PaaT protein in Penicillium chrysogenum

• Published in: Applied microbiology and biotechnology Vol. 97; no. 7; pp. 3073 - 3084
• Main Authors: Fernández-Aguado, Marta, Ullán, Ricardo V., Teijeira, Fernando, Rodríguez-Castro, Raquel, Martín, Juan F.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.04.2013; Springer Nature B.V
• Subjects: Acremonium chrysogenum; Analysis; Applied Microbial and Cell Physiology; Biological Transport; Biomedical and Life Sciences; Biosynthesis; Biotechnology; Computational Biology; Enzymes; Fungi; Gene Expression; Gene Knockdown Techniques; Genes; Genomes; Intracellular Membranes - metabolism; Life Sciences; Localization; Membrane Transport Proteins - genetics; Membrane Transport Proteins - metabolism; Membranes; Metabolites; Microbial Genetics and Genomics; Microbiology; Microscopy; Penicillin; Penicillins - biosynthesis; Penicillium chrysogenum; Penicillium chrysogenum - genetics; Penicillium chrysogenum - metabolism; Peroxisomes - metabolism; Phenylacetates - metabolism; Proteins; Secondary metabolites; Studies; Translocation; Peroxisomal membrane protein; Phenylacetic acid; Penicillin biosynthetic pathway; MFS transporter
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-012-4425-1

Penicillium chrysogenum , an industrial microorganism used worldwide for penicillin production, is an excellent model to study the biochemistry and the cell biology of enzymes involved in the synthesis of secondary metabolites. The well-known peroxisomal location of the last two steps of penicillin biosynthesis (phenylacetyl–CoA ligase and isopenicillin N acyltransferase) requires the import into the peroxisomes of the intermediate isopenicillin N and the precursors phenylacetic acid and coenzyme A. The mechanisms for the molecular transport of these precursors are still poorly understood. In this work, a search was made, in the genome of P. chrysogenum , in order to find a Major Facilitator Superfamily (MFS) membrane protein homologous to CefT of Acremonium chrysogenum , which is known to confer resistance to phenylacetic acid. The paaT gene was found to encode a MFS membrane protein containing 12 transmembrane spanners and one Pex19p-binding domain for Pex19-mediated targeting to peroxisomal membranes. RNA interference-mediated silencing of the paaT gene caused a clear reduction of benzylpenicillin secretion and increased the sensitivity of P. chrysogenum to the penicillin precursor phenylacetic acid. The opposite behavior was found when paaT was overexpressed from the glutamate dehydrogenase promoter that increases phenylacetic acid resistance and penicillin production. Localization studies by fluorescent laser scanning microscopy using PaaT–DsRed and EGFP–SKL fluorescent fusion proteins clearly showed that the protein was located in the peroxisomal membrane. The results suggested that PaaT is involved in penicillin production, most likely through the translocation of side-chain precursors (phenylacetic acid and phenoxyacetic acid) from the cytosol to the peroxisomal lumen across the peroxisomal membrane of P. chrysogenum .