TY - JOUR
T1 - The low-nanomolar 4-nitrobenzoate-responsive repressor PnbX negatively regulates the actinomycete-derived 4-nitrobenzoate-degrading pnb locus
AU - Cheng, Minggen
AU - Qian, Yingying
AU - Xing, Ziyu
AU - Zylstra, Gerben J.
AU - Huang, Xing
N1 - Funding Information:
This work was financially supported by the National Natural Science Foundation of China (Grants no. 41977119, 31800095 and 32170126) and the Natural Science Foundation of Jiangsu Province (Grants no. BK20180541).
Publisher Copyright:
© 2021 Society for Applied Microbiology and John Wiley & Sons Ltd.
PY - 2021/11
Y1 - 2021/11
N2 - Nitroaromatic compounds pose severe threats to public health and environmental safety. Nitro group removal via ammonia release is an important strategy for bacterial detoxification of nitroaromatic compounds, such as the conversion of 4-nitrobenzoate (4-NBA) to protocatechuate by the bacterial pnb operon. In contrast to the LysR-family transcriptional regulator PnbR in proteobacteria, the actinomycete-derived pnb locus (4-NBA degradation structural genes) formed an operon with the TetR-family transcriptional regulator gene pnbX, implying that it has a distinct regulatory mechanism. Here, pnbBA from the actinomycete Nocardioides sp. strain LMS-CY was biochemically confirmed to express 4-NBA degradation enzymes, and pnbX was essential for inducible degradation of 4-NBA. Purified PnbX-6His could bind the promoter probe of the pnb locus in vitro, and 4-NBA prevented this binding. 4-NBA could bind PnbX at a 1:1 molar ratio with KD = 26.7 ± 4.2 nM. Low-nanomolar levels of 4-NBA induced the transcription of the pnb operon in strain LMS-CY. PnbX bound a palindromic sequence motif (5'-TTACGTTACA-N8-TGTAACGTAA-3′) that encompasses the pnb promoter. This study identified a TetR-family repressor for the actinomycete-derived pnb operon that recognizes 10−8 M 4-NBA as its ligand, implying that nitro group removal of nitroaromatic compounds may be especially important for actinomycetes.
AB - Nitroaromatic compounds pose severe threats to public health and environmental safety. Nitro group removal via ammonia release is an important strategy for bacterial detoxification of nitroaromatic compounds, such as the conversion of 4-nitrobenzoate (4-NBA) to protocatechuate by the bacterial pnb operon. In contrast to the LysR-family transcriptional regulator PnbR in proteobacteria, the actinomycete-derived pnb locus (4-NBA degradation structural genes) formed an operon with the TetR-family transcriptional regulator gene pnbX, implying that it has a distinct regulatory mechanism. Here, pnbBA from the actinomycete Nocardioides sp. strain LMS-CY was biochemically confirmed to express 4-NBA degradation enzymes, and pnbX was essential for inducible degradation of 4-NBA. Purified PnbX-6His could bind the promoter probe of the pnb locus in vitro, and 4-NBA prevented this binding. 4-NBA could bind PnbX at a 1:1 molar ratio with KD = 26.7 ± 4.2 nM. Low-nanomolar levels of 4-NBA induced the transcription of the pnb operon in strain LMS-CY. PnbX bound a palindromic sequence motif (5'-TTACGTTACA-N8-TGTAACGTAA-3′) that encompasses the pnb promoter. This study identified a TetR-family repressor for the actinomycete-derived pnb operon that recognizes 10−8 M 4-NBA as its ligand, implying that nitro group removal of nitroaromatic compounds may be especially important for actinomycetes.
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U2 - 10.1111/1462-2920.15787
DO - 10.1111/1462-2920.15787
M3 - Article
C2 - 34554625
AN - SCOPUS:85115754691
SN - 1462-2912
VL - 23
SP - 7028
EP - 7041
JO - Environmental microbiology
JF - Environmental microbiology
IS - 11
ER -