The gene encoding a catalase-peroxidase (KatG) was cloned from chromosomal DNA of a fast-growing Mycobacterium sp. strain JC1 DSM 3803. The nucleotide sequence of a 5.7 kb EcoRI fragment containing the katG and its flanking regions was determined. The fragment (5,706 bps) contained two complete open reading frames (ORFs) encoding putative ferric uptake regulator A (FurA) and KatG proteins. The cloned gene, katG, had an ORF of 2241 nt, encoding a protein with calculated molecular mass of 81,748 Da. The furA was located in the upstream of the katG with the same transcriptional direction and there was a 38 bp gap space between them. The deduced KatG and FurA protein sequences showed significant homologies to KatG2 and Fur2 of Mycobacterium smegmatis and clustered with other mycobacterial KatG and Fur-like proteins in phylogenetic trees, respectively. The recombinant KatG overproduced in Escherichia coli was nearly indistinguishable from the native JC1 catalase-peroxidase in enzymatic properties and also possessed the resistance to organic solvents, indicating that the cloned katG truly encodes the Mycobacterium sp. JC1 catalase-peroxidase. Difference spectroscopy revealed Mn(II) binding near the haem of the KatG. Transcript analysis of the furA-katG using RT-PCR suggests that the katG is independently transcribed from the furA.
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Nat Microbiol
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Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, USA.
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College of Agriculture and Forestry, Linyi University, Linyi, 276005, Shandong, China.
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Department of Chemistry, Loker Hydrocarbon Research Institute, University of Southern California, Los Angeles, California 90089, United States.
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Department of Bacterial Disease Research, Center for Infectious Disease Research, National Institute of Infectious Disease, National Institute of Health, Korea Disease Control and Prevention Agency, Cheongju-si, South Korea.
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Department of Environmental and Chemical Engineering, Shanghai University, Nanchen Rd. 333, Shanghai, China.
Photodynamic therapy (PDT) has been used clinically to treat superficial tumors for decades. However, its effectiveness against deep-seated tumors has been limited by the inefficient delivery of the key components -light, photosensitizer, and oxygen- required for the photochemical reactions in PDT. Here, we present a novel platform that enables the photochemical reaction to occur in a self-driven manner, eliminating the need for external delivery of these components and instead orchestrating their endogenous generation within tumors.
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