AUTHOR=Yang Wenjun , Ruan Lifang , Tao Jiangming , Peng Donghai , Zheng Jinshui , Sun Ming 

TITLE=Single Amino Acid Substitution in Homogentisate Dioxygenase Affects Melanin Production in Bacillus thuringiensis

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.02242

DOI=10.3389/fmicb.2018.02242

ISSN=1664-302X

ABSTRACT=<p><italic>Bacillus thuringiensis</italic> formulation losing its activity under field conditions due to UV radiation and photoprotection of <italic>B. thuringiensis</italic> based on melanin has attracted the attention of researchers for many years. Here, a single amino acid substitution (G272E) in homogentisate 1,2-dioxygenase was found to be responsible for pigment overproduction in <italic>B. thuringiensis</italic> BMB181, a derivative of BMB171. Disrupting the gene encoding homogentisate dioxygenase in BMB171 induced the accumulation of the homogentisic acid and provoked an increased pigment formation. To gain insights into homogentisate 1,2-dioxygenase in <italic>B. thuringiensis</italic>, we constructed a total of 14 mutations with a single amino acid substitution, and six of the mutant proteins were found to affect the melanin production when substituted by alanine. This study provides a new way to construct pigment-overproducing strains by impairing the homogentisate dioxygenase with a single mutation in <italic>B. thuringiensis</italic>, and the findings will facilitate a better understanding of this enzyme.</p>