Disruption of the siderophore-binding desE
 receptor gene in Streptomyces coelicolor
 A3(2) results in impaired growth in spite of multiple iron-siderophore transport systems

Streptomyces spp. are known to produce various types of biologically active compounds including antibiotics, antiparasitic agents, herbicides and immunosuppressants. P450 (cytochrome P450) enzymes may have key roles in these biosynthetic and biotransformation reactions. Recent genomic analysis of Streptomyces coelicolor A3(2) indicates that S. coelicolor may have six ferredoxins (Fdxs), four putative Fdx reductases (FdRs) and 18 P450 genes. However, there are few clues to explain the mechanisms and functions of Streptomyces P450 systems. To solve these questions, we have expressed and purified five S. coelicolor P450s, four FdRs and six Fdxs in Escherichia coli. Of the purified P450s, CYP105D5 has fatty acid hydroxylation activity in a system reconstituted with putidaredoxin reductase and Fdx4 or with spinach FdR and spinach Fdx, although the reconstitutions with FdR2 or FdR3 and any of the Fdxs did not support CYP105D5-catalysed oleic acid hydroxylation. Elucidation of the detailed mechanisms of electron transport system for Streptomyces P450 may provide the perspective for usefulness of P450s as a biocatalyst.

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The Zinc-Responsive Regulator Zur Controls a Zinc Uptake System and Some Ribosomal Proteins in Streptomyces coelicolor A3(2)

Journal of Bacteriology ◽

10.1128/jb.01851-06 ◽

2007 ◽

Vol 189 (11) ◽

pp. 4070-4077 ◽

Cited By ~ 69

Author(s):

Jung-Ho Shin ◽

So-Young Oh ◽

Soon-Jong Kim ◽

Jung-Hye Roe

Keyword(s):

Ribosomal Proteins ◽

Streptomyces Coelicolor ◽

Regulatory System ◽

Repeat Sequence ◽

Zinc Uptake ◽

Zinc Homeostasis ◽

Transport Systems ◽

Binding Motif ◽

Uptake System ◽

Zinc Depletion

ABSTRACT In various bacteria, Zur, a zinc-specific regulator of the Fur family, regulates genes for zinc transport systems to maintain zinc homeostasis. It has also been suggested that Zur controls zinc mobilization by regulating some ribosomal proteins. The antibiotic-producing soil bacterium Streptomyces coelicolor contains four genes for Fur family regulators, and one (named zur) is located downstream of the znuACB operon encoding a putative zinc uptake transporter. We found that zinc specifically repressed the level of znuA transcripts and that this level was derepressed in a Δzur mutant. Purified Zur existing as homodimers bound to the znuA promoter region in the presence of zinc, confirming the role of Zur as a zinc-responsive repressor. We analyzed transcripts for paralogous forms of ribosomal proteins L31 (RpmE1 and RpmE2) and L33 (RpmG2 and RpmG3) for their dependence on Zur and found that RpmE2 and RpmG2 with no zinc-binding motif of conserved cysteines (C's) were negatively regulated by Zur. C-negative RpmG3 and C-positive RpmE1 were not regulated by Zur. Instead, they were regulated by the sigma factor σR as predicted from their promoter sequences. The rpmE1 and rpmG3 genes were partially induced by EDTA in a manner dependent on σR, suggesting that zinc depletion may stimulate the σR regulatory system. This finding reflects a link between thiol-oxidizing stress and zinc depletion. We determined the Zur-binding sites within znuA and rpmG2 promoter regions by footprinting analyses and identified a consensus inverted repeat sequence (TGaaAatgatTttCA, where uppercase letters represent the nucleotides common to all sites analyzed). This sequence closely matches that for mycobacterial Zur and allows the prediction of more genes in the Zur regulon.

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Influence of rehydration on transcriptome during resuscitation of desiccated Pseudomonas putida KT2440

Annals of Microbiology ◽

10.1186/s13213-020-01596-3 ◽

2020 ◽

Vol 70 (1) ◽

Author(s):

Lilia I. López-Lara ◽

Laura A. Pazos-Rojas ◽

Lesther E. López-Cruz ◽

Yolanda E. Morales-García ◽

Verónica Quintero-Hernández ◽

...

Keyword(s):

Protein Synthesis ◽

Pseudomonas Putida ◽

Receptor Gene ◽

Transport Processes ◽

Desiccation Stress ◽

Transport Systems ◽

Vbnc State ◽

Pseudomonas Putida Kt2440 ◽

Oxidation Reduction ◽

Alcohol Transport

Abstract Purpose Pseudomonas putida KT2440 is a desiccation-sensitive bacterium that loses culturability after 15 days of air desiccation. We have previously shown that P. putida KT2440 can develop a viable but nonculturable (VBNC) state after being exposed to desiccation stress and eventually recover when desiccated cells are rehydrated for at least 24 h. Methods To determine which genes of transport, oxidation-reduction, and transcription processes could be involved in the return of P. putida KT2440 to the culturable state, a transcriptome analysis was carried out comparing the gene expression of non-desiccated samples with samples subjected to desiccation followed by 20 min of rehydration or desiccation followed by 24 h of rehydration. Results Desiccation stress triggered a VBNC state of P. putida. The major response was detected after 24 h of rehydration with 148 upregulated and 42 downregulated genes. During the VBNC state, P. putida activated transmembrane transport processes like that of siderophores through a TonB-dependent transporter and putative polyhydric alcohol transport systems. Prolonged rehydration with distilled water resuscitated P. putida KT2440 cells activating the catabolism of phenylalanine/tyrosine to provide energy and carbon for ubiquinone biosynthesis while maintaining a reduced protein synthesis. On the other hand, the interruption of the TonB-dependent receptor gene (PP_1446) increased desiccation survival of the mutant strain. Conclusion The activation of the iron transport system (TonB-dependent siderophore receptor) and alcohol transport can be helping the VBNC state of P. putida. Activation of catabolism of phenylalanine/tyrosine and reduced protein synthesis was needed for resuscitation from the VBNC state.

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Positive Control of Ferric Siderophore Receptor Gene Expression by the Irr Protein in Bradyrhizobium japonicum

Journal of Bacteriology ◽

10.1128/jb.01571-08 ◽

2008 ◽

Vol 191 (5) ◽

pp. 1361-1368 ◽

Cited By ~ 29

Author(s):

Sandra K. Small ◽

Sumant Puri ◽

Indu Sangwan ◽

Mark R. O'Brian

Keyword(s):

Bradyrhizobium Japonicum ◽

Iron Transport ◽

Ferric Iron ◽

Receptor Gene ◽

Regulatory Protein ◽

Transport Systems ◽

Control Element ◽

Iron Chelate ◽

Cell Extracts

ABSTRACT Ferric siderophore receptors are components of high-affinity iron-chelate transport systems in gram-negative bacteria. The genes encoding these receptors are generally regulated by repression. Here, we show that the ferrichrome receptor gene bll4920 and four additional putative ferric siderophore receptor genes in Bradyrhizobium japonicum are positively controlled by the regulatory protein Irr, as observed by the low level of mRNA transcripts in an irr mutant in iron-limited cells. Potential Irr binding sites with iron control element (ICE)-like motifs were found upstream and distal to the transcription start sites of the five receptor genes. However, purified recombinant Irr bound only some of those elements. Nevertheless, dissection of the bll4920 promoter region showed that a component in extracts of wild-type cells grown in iron-limited media bound only in the ICE motif region of the promoter. This binding was not observed with extracts of cells from the parent strain grown under high-iron conditions or from an irr mutant strain. Furthermore, gel mobility supershift experiments identified Irr as the binding protein in cell extracts. Chromatin immunoprecipitation experiments demonstrated that Irr occupies the promoters of the five ferric iron transport genes in vivo. We conclude that Irr is a direct positive regulator of ferric iron transport in B. japonicum.

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