Manganese-dependent peroxidase from Phanerochaete chrysosporium. Primary structure deduced from cDNA sequence

Area of Science:

• Biochemistry
• Molecular Biology
• Mycology

Background:

• Phanerochaete chrysosporium produces extracellular lignin-degrading enzymes.
• Manganese-dependent peroxidase is a key enzyme in lignin degradation.
• Understanding the genetic basis of peroxidase production is crucial for biotechnological applications.

Purpose of the Study:

• To isolate and characterize the cDNA encoding manganese-dependent peroxidase from P. chrysosporium.
• To analyze the deduced amino acid sequence for functional insights.
• To investigate the transcriptional regulation of manganese-dependent peroxidase expression.

Main Methods:

• Screening of a lambda gt11 expression library using specific antibodies.
• Nucleotide sequencing of the isolated cDNA clone (lambda MP-1).
• N-terminal amino acid sequencing of the purified enzyme.
• Northern blot analysis of poly(A)+ RNA.

Main Results:

• Isolation and characterization of lambda MP-1, a cDNA encoding manganese-dependent peroxidase.
• The cDNA predicts a mature protein of 358 amino acids with significant homology to lignin peroxidase.
• Essential active site residues (histidines) were identified, and homology was observed with other peroxidases.
• Messenger RNA levels correlate with enzyme expression, suggesting transcriptional regulation.

Conclusions:

• The study provides the cDNA sequence for P. chrysosporium manganese-dependent peroxidase.
• The findings reveal structural similarities and conserved active sites with other peroxidases.
• Enzyme expression is regulated at the transcriptional level in response to environmental cues (nitrogen limitation).