TY - JOUR
T1 - A transcriptional regulator, IscR, of Burkholderia multivorans acts as both repressor and activator for transcription of iron-sulfur cluster-biosynthetic isc operon
AU - Nonoyama, Shouta
AU - Kishida, Kouhei
AU - Sakai, Keiichiro
AU - Nagata, Yuji
AU - Ohtsubo, Yoshiyuki
AU - Tsuda, Masataka
N1 - Funding Information:
We are grateful to Dr. Yasuhiro Takahashi (Saitama University) for providing UT109(pUMV22Sp) and Dr. Jun Kaneko (Tohoku University) for the use of anaerobic chamber. This work was supported by a Grant-in-Aid from the Ministry of Education, Culture, Sports, Science and Technology, Japan ( 17H03781 ).
Publisher Copyright:
© 2020 Institut Pasteur
PY - 2020/12
Y1 - 2020/12
N2 - Bacterial iron-sulfur (Fe–S) clusters are essential cofactors for many metabolic pathways, and Fe–S cluster-containing proteins (Fe–S proteins) regulate the expression of various important genes. However, biosynthesis of such clusters has remained unknown in genus Burkholderia. Here, we clarified that Burkholderia multivorans ATCC 17616 relies on the ISC system for the biosynthesis of Fe–S clusters, and that the biosynthetic genes are organized as an isc operon, whose first gene encodes IscR, a transcriptional regulatory Fe–S protein. Transcription of the isc operon was repressed and activated under iron-rich and -limiting conditions, respectively, and Fur, an iron-responsive global transcriptional regulator, was indicated to indirectly regulate the expression of isc operon. Further analysis using a ΔiscR mutant in combination with a constitutive expression system of IscR and its derivatives indicated transcriptional repression and activation of isc operon by holo- and apo-forms of IscR, respectively, through their binding to the sequences within an isc promoter-containing (Pisc) fragment. Biochemical analysis using the Pisc fragment suggested that the apo-IscR binding sequence differs from the holo-IscR binding sequence. The results obtained in this study revealed a unique regulatory system for the expression of the ATCC 17616 isc operon that has not been observed in other genera.
AB - Bacterial iron-sulfur (Fe–S) clusters are essential cofactors for many metabolic pathways, and Fe–S cluster-containing proteins (Fe–S proteins) regulate the expression of various important genes. However, biosynthesis of such clusters has remained unknown in genus Burkholderia. Here, we clarified that Burkholderia multivorans ATCC 17616 relies on the ISC system for the biosynthesis of Fe–S clusters, and that the biosynthetic genes are organized as an isc operon, whose first gene encodes IscR, a transcriptional regulatory Fe–S protein. Transcription of the isc operon was repressed and activated under iron-rich and -limiting conditions, respectively, and Fur, an iron-responsive global transcriptional regulator, was indicated to indirectly regulate the expression of isc operon. Further analysis using a ΔiscR mutant in combination with a constitutive expression system of IscR and its derivatives indicated transcriptional repression and activation of isc operon by holo- and apo-forms of IscR, respectively, through their binding to the sequences within an isc promoter-containing (Pisc) fragment. Biochemical analysis using the Pisc fragment suggested that the apo-IscR binding sequence differs from the holo-IscR binding sequence. The results obtained in this study revealed a unique regulatory system for the expression of the ATCC 17616 isc operon that has not been observed in other genera.
KW - Burkholderia multivorans
KW - Fe–S cluster
KW - Iron
KW - IscR
KW - Transcriptional regulation
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U2 - 10.1016/j.resmic.2020.06.005
DO - 10.1016/j.resmic.2020.06.005
M3 - Article
C2 - 32628999
AN - SCOPUS:85087951482
VL - 171
SP - 319
EP - 330
JO - Research in Microbiology
JF - Research in Microbiology
SN - 0923-2508
IS - 8
ER -