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Unique Properties of the Alpha-Helical DNA-Binding Protein KfrA Encoded by the IncU Incompatibility Group Plasmid RA3 and Its Host-Dependent Role in Plasmid Maintenance
KfrA, encoded on the broad-host-range RA3 plasmid, is an alpha-helical DNA-binding protein that acts as a transcriptional autoregulator. The KfrA(RA3) operator site overlaps the kfrA promoter and is composed of five 9-bp direct repeats (DRs). Here, the biological properties of KfrA were studied usin...
Autores principales: | , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
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American Society for Microbiology
2021
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7783346/ https://www.ncbi.nlm.nih.gov/pubmed/33097508 http://dx.doi.org/10.1128/AEM.01771-20 |
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author | Lewicka, Ewa Mitura, Monika Steczkiewicz, Kamil Kieracinska, Justyna Skrzynska, Kamila Adamczyk, Malgorzata Jagura-Burdzy, Grazyna |
author_facet | Lewicka, Ewa Mitura, Monika Steczkiewicz, Kamil Kieracinska, Justyna Skrzynska, Kamila Adamczyk, Malgorzata Jagura-Burdzy, Grazyna |
author_sort | Lewicka, Ewa |
collection | PubMed |
description | KfrA, encoded on the broad-host-range RA3 plasmid, is an alpha-helical DNA-binding protein that acts as a transcriptional autoregulator. The KfrA(RA3) operator site overlaps the kfrA promoter and is composed of five 9-bp direct repeats (DRs). Here, the biological properties of KfrA were studied using both in vivo and in vitro approaches. Localization of the DNA-binding helix-turn-helix motif (HTH) was mapped to the N29-R52 region by protein structure modeling and confirmed by alanine scanning. KfrA repressor ability depended on the number and orientation of DRs in the operator, as well as the ability of the protein to oligomerize. The long alpha-helical tail from residues 54 to 355 was shown to be involved in self-interactions, whereas the region from residue 54 to 177 was involved in heterodimerization with KfrC, another RA3-encoded alpha-helical protein. KfrA also interacted with the segrosome proteins IncC (ParA) and KorB (ParB), representatives of the class Ia active partition systems. Deletion of the kfr genes from the RA3 stability module decreased the plasmid retention in diverse hosts in a species-dependent manner. The specific interactions of KfrA with DNA are essential not only for the transcriptional regulatory function but also for the accessory role of KfrA in stable plasmid maintenance. IMPORTANCE Alpha-helical coiled-coil KfrA-type proteins are encoded by various broad-host-range low-copy-number conjugative plasmids. The DNA-binding protein KfrA encoded on the RA3 plasmid, a member of the IncU incompatibility group, oligomerizes, forms a complex with another plasmid-encoded, alpha-helical protein, KfrC, and interacts with the segrosome proteins IncC and KorB. The unique mode of KfrA dimer binding to the repetitive operator is required for a KfrA role in the stable maintenance of RA3 plasmid in distinct hosts. |
format | Online Article Text |
id | pubmed-7783346 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2021 |
publisher | American Society for Microbiology |
record_format | MEDLINE/PubMed |
spelling | pubmed-77833462021-01-29 Unique Properties of the Alpha-Helical DNA-Binding Protein KfrA Encoded by the IncU Incompatibility Group Plasmid RA3 and Its Host-Dependent Role in Plasmid Maintenance Lewicka, Ewa Mitura, Monika Steczkiewicz, Kamil Kieracinska, Justyna Skrzynska, Kamila Adamczyk, Malgorzata Jagura-Burdzy, Grazyna Appl Environ Microbiol Genetics and Molecular Biology KfrA, encoded on the broad-host-range RA3 plasmid, is an alpha-helical DNA-binding protein that acts as a transcriptional autoregulator. The KfrA(RA3) operator site overlaps the kfrA promoter and is composed of five 9-bp direct repeats (DRs). Here, the biological properties of KfrA were studied using both in vivo and in vitro approaches. Localization of the DNA-binding helix-turn-helix motif (HTH) was mapped to the N29-R52 region by protein structure modeling and confirmed by alanine scanning. KfrA repressor ability depended on the number and orientation of DRs in the operator, as well as the ability of the protein to oligomerize. The long alpha-helical tail from residues 54 to 355 was shown to be involved in self-interactions, whereas the region from residue 54 to 177 was involved in heterodimerization with KfrC, another RA3-encoded alpha-helical protein. KfrA also interacted with the segrosome proteins IncC (ParA) and KorB (ParB), representatives of the class Ia active partition systems. Deletion of the kfr genes from the RA3 stability module decreased the plasmid retention in diverse hosts in a species-dependent manner. The specific interactions of KfrA with DNA are essential not only for the transcriptional regulatory function but also for the accessory role of KfrA in stable plasmid maintenance. IMPORTANCE Alpha-helical coiled-coil KfrA-type proteins are encoded by various broad-host-range low-copy-number conjugative plasmids. The DNA-binding protein KfrA encoded on the RA3 plasmid, a member of the IncU incompatibility group, oligomerizes, forms a complex with another plasmid-encoded, alpha-helical protein, KfrC, and interacts with the segrosome proteins IncC and KorB. The unique mode of KfrA dimer binding to the repetitive operator is required for a KfrA role in the stable maintenance of RA3 plasmid in distinct hosts. American Society for Microbiology 2021-01-04 /pmc/articles/PMC7783346/ /pubmed/33097508 http://dx.doi.org/10.1128/AEM.01771-20 Text en Copyright © 2021 Lewicka et al. https://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license (https://creativecommons.org/licenses/by/4.0/) . |
spellingShingle | Genetics and Molecular Biology Lewicka, Ewa Mitura, Monika Steczkiewicz, Kamil Kieracinska, Justyna Skrzynska, Kamila Adamczyk, Malgorzata Jagura-Burdzy, Grazyna Unique Properties of the Alpha-Helical DNA-Binding Protein KfrA Encoded by the IncU Incompatibility Group Plasmid RA3 and Its Host-Dependent Role in Plasmid Maintenance |
title | Unique Properties of the Alpha-Helical DNA-Binding Protein KfrA Encoded by the IncU Incompatibility Group Plasmid RA3 and Its Host-Dependent Role in Plasmid Maintenance |
title_full | Unique Properties of the Alpha-Helical DNA-Binding Protein KfrA Encoded by the IncU Incompatibility Group Plasmid RA3 and Its Host-Dependent Role in Plasmid Maintenance |
title_fullStr | Unique Properties of the Alpha-Helical DNA-Binding Protein KfrA Encoded by the IncU Incompatibility Group Plasmid RA3 and Its Host-Dependent Role in Plasmid Maintenance |
title_full_unstemmed | Unique Properties of the Alpha-Helical DNA-Binding Protein KfrA Encoded by the IncU Incompatibility Group Plasmid RA3 and Its Host-Dependent Role in Plasmid Maintenance |
title_short | Unique Properties of the Alpha-Helical DNA-Binding Protein KfrA Encoded by the IncU Incompatibility Group Plasmid RA3 and Its Host-Dependent Role in Plasmid Maintenance |
title_sort | unique properties of the alpha-helical dna-binding protein kfra encoded by the incu incompatibility group plasmid ra3 and its host-dependent role in plasmid maintenance |
topic | Genetics and Molecular Biology |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7783346/ https://www.ncbi.nlm.nih.gov/pubmed/33097508 http://dx.doi.org/10.1128/AEM.01771-20 |
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