scholarly journals Free Fatty Acids Interfere with the DNA Binding Activity of the Virulence Regulator PrfA of Listeria monocytogenes

2020 ◽  
Vol 202 (15) ◽  
Author(s):  
Patrícia T. dos Santos ◽  
Rikke S. S. Thomasen ◽  
Mathias S. Green ◽  
Nils J. Færgeman ◽  
Birgitte H. Kallipolitis
Keyword(s):  
Fatty Acids ◽  
Dna Binding ◽  
Free Fatty Acids ◽  
Antimicrobial Agents ◽  
Virulence Gene ◽  
Binding Activity ◽  
Content Type ◽  
Dna Binding Activity ◽  
Virulence Regulator ◽  
Long Chain

ABSTRACT Naturally occurring free fatty acids (FFAs) are recognized as potent antimicrobial agents that also affect the production of virulence factors in bacterial pathogens. In the foodborne pathogen Listeria monocytogenes, some medium- and long-chain FFAs act as antimicrobial agents as well as signaling compounds, causing a repression of transcription of virulence genes. We previously observed that the master virulence regulator PrfA is involved in both the antimicrobial and virulence-inhibitory response of L. monocytogenes to selected FFAs, but the underlying mechanisms are presently unknown. Here, we present a systematic analysis of the antimicrobial and PrfA-inhibitory activities of medium- and long-chain FFAs of various carbon chain lengths and degrees of saturation. We observed that exposure to specific antimicrobial and nonantimicrobial FFAs prevented PrfA-dependent activation of virulence gene transcription and reduced the levels of PrfA-regulated virulence factors. Thus, an antimicrobial activity was not compulsory for the PrfA-inhibitory ability of an FFA. In vitro binding experiments revealed that PrfA-inhibitory FFAs were also able to prevent the constitutively active variant PrfA* from binding to the PrfA box in the promoter region of the virulence gene hly, whereas noninhibitory FFAs did not affect its ability to bind DNA. Notably, the unsaturated FFAs inhibited the DNA binding activity of PrfA* most efficiently. Altogether, our findings support a model in which specific FFAs orchestrate a generalized reduction of the virulence potential of L. monocytogenes by directly targeting the key virulence regulator PrfA. IMPORTANCE Listeria monocytogenes is a Gram-positive pathogen able to cause foodborne infections in humans and animals. Key virulence genes in L. monocytogenes are activated by the transcription regulator PrfA, a DNA binding protein belonging to the CRP/FNR family. Various signals from the environment are known to affect the activity of PrfA, either positively or negatively. Recently, we found that specific medium- and long-chain free fatty acids act as antimicrobial agents as well as signaling compounds in L. monocytogenes. Here, we show that both antimicrobial and nonantimicrobial free fatty acids inhibit PrfA-dependent activation of virulence gene transcription by interfering with the DNA binding activity of PrfA. Our findings suggest that free fatty acids could be candidates for alternative therapies against L. monocytogenes.

The inhibitory action of long-chain fatty acids on the DNA binding activity of p53

Lipids ◽  
2006 ◽  
Vol 41 (6) ◽  
pp. 521-527 ◽  
Author(s):  
Hiroshi Iijima ◽  
Nobuyuki Kasai ◽  
Hiroyuki Chiku ◽  
Shizuka Murakami ◽  
Fumio Sugawara ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Dna Binding ◽  
Inhibitory Action ◽  
Binding Activity ◽  
Long Chain Fatty Acids ◽  
Dna Binding Activity ◽  
Long Chain ◽  
Chain Fatty Acids

scholarly journals Toll-Like Receptor Stimulation Induces Nondefensin Protein Expression and Reverses Antibiotic-Induced Gut Defense Impairment

2014 ◽  
Vol 82 (5) ◽  
pp. 1994-2005 ◽  
Author(s):  
Ying-Ying Wu ◽  
Ching-Mei Hsu ◽  
Pei-Hsuan Chen ◽  
Chang-Phone Fung ◽  
Lee-Wei Chen
Keyword(s):  
Dna Binding ◽  
Protein Expression ◽  
Antibiotic Treatment ◽  
Intestinal Mucosa ◽  
Pathogenic Bacteria ◽  
Binding Activity ◽  
Toll Like Receptor ◽  
Content Type ◽  
Killing Activity ◽  
Dna Binding Activity

ABSTRACTPrior antibiotic exposure is associated with increased mortality in Gram-negative bacteria-induced sepsis. However, how antibiotic-mediated changes of commensal bacteria promote the spread of enteric pathogenic bacteria in patients remains unclear. In this study, the effects of systemic antibiotic treatment with or without Toll-like receptor (TLR) stimulation on bacterium-killing activity, antibacterial protein expression in the intestinal mucosa, and bacterial translocation were examined in mice receiving antibiotics with or without oral supplementation of deadEscherichia coliorStaphylococcus aureus. We developed a systemic ampicillin, vancomycin, and metronidazole treatment protocol to simulate the clinical use of antibiotics. Antibiotic treatment decreased the total number of bacteria, including aerobic bacteria belonging to the familyEnterobacteriaceaeand the genusEnterococcusas well as organisms of the anaerobic generaLactococcusandBifidobacteriumin the intestinal mucosa and lumen. Antibiotic treatment significantly decreased the bacterium-killing activity of the intestinal mucosa and the expression of non-defensin-family proteins, such as RegIIIβ, RegIIIγ, C-reactive protein-ductin, and RELMβ, but not the defensin-family proteins, and increasedKlebsiella pneumoniaetranslocation. TLR stimulation after antibiotic treatment increased NF-κB DNA binding activity, nondefensin protein expression, and bacterium-killing activity in the intestinal mucosa and decreasedK. pneumoniaetranslocation. Moreover, germfree mice showed a significant decrease in nondefensin proteins as well as intestinal defense against pathogen translocation. Since TLR stimulation induced NF-κB DNA binding activity, TLR4 expression, and mucosal bacterium-killing activity in germfree mice, we conclude that the commensal microflora is critical in maintaining intestinal nondefensin protein expression and the intestinal barrier. In turn, we suggest that TLR stimulation induces nondefensin protein expression and reverses antibiotic-induced gut defense impairment.

scholarly journals BosR Is A Novel Fur Family Member Responsive to Copper and Regulating Copper Homeostasis in Borrelia burgdorferi

2017 ◽  
Vol 199 (16) ◽  
Author(s):  
Peng Wang ◽  
Zhuoteng Yu ◽  
Thomas J. Santangelo ◽  
John Olesik ◽  
Yufeng Wang ◽  
...  
Keyword(s):  
Dna Binding ◽  
Borrelia Burgdorferi ◽  
Metal Ions ◽  
Metal Ion ◽  
Transition Metal Ions ◽  
Binding Activity ◽  
Ferric Uptake Regulator ◽  
Content Type ◽  
Dna Binding Activity ◽  
Cu Homeostasis

ABSTRACT The ferric uptake regulator (Fur) family of DNA-binding proteins represses and/or activates gene transcription via divalent metal ion-dependent signal sensing. The Borrelia burgdorferi Fur homologue, also known as Borrelia oxidative stress regulator (BosR), promotes spirochetal adaptation to the mammalian host by directly repressing the lipoproteins required for tick colonization and indirectly activating those required for establishing infection in the mammal. Here, we examined whether the DNA-binding activity of BosR was regulated by any of the four most prevalent transition metal ions in B. burgdorferi, Mn, Fe, Cu, and Zn. Our data indicated that in addition to a structural site occupied by Zn(II), BosR had two regulatory sites that could be occupied by Zn(II), Fe(II), or Cu(II) but not by Mn(II). While Fe(II) had no effect, Cu(II) and Zn(II) had a dose-dependent inhibitory effect on the BosR DNA-binding activity. Competition experiments indicated that Cu(II) had a higher affinity for BosR than Zn(II) or Fe(II). A BosR deficiency in B. burgdorferi resulted in a significant increase in the Cu level but no significant change in the levels of Mn, Fe, or Zn. These data suggest that Cu regulates BosR activity, and BosR in turn regulates Cu homeostasis in B. burgdorferi. While this regulatory paradigm is characteristic of the Fur family, BosR is the first one shown to be responsive to Cu(II), which may be an adaptation to the potentially high level of Cu present in the Lyme disease spirochete. IMPORTANCE Transition metal ions serve an essential role in the metabolism of all living organisms. Members of the ferric uptake regulator (Fur) family play critical roles in regulating the cellular homeostasis of transition metals in diverse bacteria, and their DNA-binding activity is often regulated by coordination of the cognate divalent metal ions. To date, regulators with metal ion specificity to Fe(II), Mn(II), Zn(II), and Ni(II) have all been described. In this study, we demonstrate that BosR, the sole Fur homologue in Borrelia burgdorferi, is responsive to Cu(II) and regulates Cu homeostasis in this bacterium, which may be an adaption to potentially Cu-rich milieu in the Lyme disease spirochete. This study has expanded the repertoire of the Fur family's metal ion specificity.

Effect of dietary saturated fatty acids on HNF-4α DNA binding activity and ApoCIII mRNA in sedentary rat liver

2010 ◽  
Vol 347 (1-2) ◽  
pp. 29-39 ◽  
Author(s):  
Veronica Ceccarelli ◽  
Giuseppe Nocentini ◽  
Carlo Riccardi ◽  
Emira Ayroldi ◽  
Paolo Di Nardo ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Dna Binding ◽  
Rat Liver ◽  
Saturated Fatty Acids ◽  
Binding Activity ◽  
Dna Binding Activity

scholarly journals Negative Regulation of Ectoine Uptake and Catabolism in Sinorhizobium meliloti: Characterization of the EhuR Gene

2016 ◽  
Vol 199 (1) ◽  
Author(s):  
Qinli Yu ◽  
Hanlin Cai ◽  
Yanfeng Zhang ◽  
Yongzhi He ◽  
Lincai Chen ◽  
...  
Keyword(s):  
Dna Binding ◽  
Sinorhizobium Meliloti ◽  
Binding Activity ◽  
Mobility Shift ◽  
Content Type ◽  
Reverse Transcription Pcr ◽  
Dna Binding Activity ◽  
Dnase I Footprinting ◽  
Gntr Family

ABSTRACT Ectoine has osmoprotective effects on Sinorhizobium meliloti that differ from its effects in other bacteria. Ectoine does not accumulate in S. meliloti cells; instead, it is degraded. The products of the ehuABCD-eutABCDE operon were previously discovered to be responsible for the uptake and catabolism of ectoine in S. meliloti. However, the mechanism by which ectoine is involved in the regulation of the ehuABCD-eutABCDE operon remains unclear. The ehuR gene, which is upstream of and oriented in the same direction as the ehuABCD-eutABCDE operon, encodes a member of the MocR/GntR family of transcriptional regulators. Quantitative reverse transcription-PCR and promoter-lacZ reporter fusion experiments revealed that EhuR represses transcription of the ehuABCD-eutABCDE operon, but this repression is inhibited in the presence of ectoine. Electrophoretic mobility shift assays and DNase I footprinting assays revealed that EhuR bound specifically to the DNA regions overlapping the −35 region of the ehuA promoter and the +1 region of the ehuR promoter. Surface plasmon resonance assays further demonstrated direct interactions between EhuR and the two promoters, although EhuR was found to have higher affinity for the ehuA promoter than for the ehuR promoter. In vitro, DNA binding by EhuR could be directly inhibited by a degradation product of ectoine. Our work demonstrates that EhuR is an important negative transcriptional regulator involved in the regulation of ectoine uptake and catabolism and is likely regulated by one or more end products of ectoine catabolism. IMPORTANCE Sinorhizobium meliloti is an important soil bacterium that displays symbiotic interactions with legume hosts. Ectoine serves as a key osmoprotectant for S. meliloti. However, ectoine does not accumulate in the cells; rather, it is degraded. In this study, we characterized the transcriptional regulation of the operon responsible for ectoine uptake and catabolism in S. meliloti. We identified and characterized the transcription repressor EhuR, which is the first MocR/GntR family member found to be involved in the regulation of compatible solute uptake and catabolism. More importantly, we demonstrated for the first time that an ectoine catabolic end product could modulate EhuR DNA-binding activity. Therefore, this work provides new insights into the unique mechanism of ectoine-induced osmoprotection in S. meliloti.

scholarly journals An Oleaginous Bacterium That Intrinsically Accumulates Long-Chain Free Fatty Acids in its Cytoplasm

2013 ◽  
Vol 80 (3) ◽  
pp. 1126-1131 ◽  
Author(s):  
Taiki Katayama ◽  
Manabu Kanno ◽  
Naoki Morita ◽  
Tomoyuki Hori ◽  
Takashi Narihiro ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Lactic Acid ◽  
16S Rrna ◽  
Cell Membrane ◽  
16S Rrna Gene ◽  
Free Fatty Acids ◽  
Biodiesel Production ◽  
Rrna Gene ◽  
Content Type ◽  
Long Chain

ABSTRACTMedium- and long-chain fatty acids are present in organisms in esterified forms that serve as cell membrane constituents and storage compounds. A large number of organisms are known to accumulate lipophilic materials as a source of energy and carbon. We found a bacterium, designated GK12, that intrinsically accumulates free fatty acids (FFAs) as intracellular droplets without exhibiting cytotoxicity. GK12 is an obligatory anaerobic, mesophilic lactic acid bacterium that was isolated from a methanogenic reactor. Phylogenetic analysis based on 16S rRNA gene sequences showed that GK12 is affiliated with the familyErysipelotrichaceaein the phylumFirmicutesbut is distantly related to type species in this family (less than 92% similarity in 16S rRNA gene sequence). Saturated fatty acids with carbon chain lengths of 14, 16, 18, and 20 were produced from glucose under stress conditions, including higher-than-optimum temperatures and the presence of organic solvents that affect cell membrane integrity. FFAs were produced at levels corresponding to up to 25% (wt/wt) of the dry cell mass. Our data suggest that FFA accumulation is a result of an imbalance between excess membrane fatty acid biosynthesis due to homeoviscous adaptation and limited β-oxidation activity due to anaerobic growth involving lactic acid fermentation. FFA droplets were not further utilized as an energy and carbon source, even under conditions of starvation. A naturally occurring bacterium that accumulates significant amounts of long-chain FFAs with noncytotoxicity would provide useful strategies for microbial biodiesel production.

scholarly journals Domain Organization of Vaccinia Virus Helicase-Primase D5

2016 ◽  
Vol 90 (9) ◽  
pp. 4604-4613 ◽  
Author(s):  
Stephanie Hutin ◽  
Wai Li Ling ◽  
Adam Round ◽  
Gregory Effantin ◽  
Stefan Reich ◽  
...  
Keyword(s):  
Dna Binding ◽  
Vaccinia Virus ◽  
Genome Structure ◽  
Antiviral Drug ◽  
Binding Activity ◽  
Structural Basis ◽  
Helicase Domain ◽  
Content Type ◽  
Dna Binding Activity ◽  
Double Stranded Dna

ABSTRACTPoxviridaeare viruses with a large linear double-stranded DNA genome coding for up to 250 open reading frames and a fully cytoplasmic replication. The double-stranded DNA genome is covalently circularized at both ends. Similar structures of covalently linked extremities of the linear DNA genome are found in the African swine fever virus (asfarvirus) and in thePhycodnaviridae. We are studying the machinery which replicates this peculiar genome structure. From our work with vaccinia virus, we give first insights into the overall structure and function of the essential poxvirus virus helicase-primase D5 and show that the active helicase domain of D5 builds a hexameric ring structure. This hexamer has ATPase and, more generally, nucleoside triphosphatase activities that are indistinguishable from the activities of full-length D5 and that are independent of the nature of the base. In addition, hexameric helicase domains bind tightly to single- and double-stranded DNA. Still, the monomeric D5 helicase construct truncated within the D5N domain leads to a well-defined structure, but it does not have ATPase or DNA-binding activity. This shows that the full D5N domain has to be present for hexamerization. This allowed us to assign a function to the D5N domain which is present not only in D5 but also in other viruses of the nucleocytoplasmic large DNA virus (NCLDV) clade. The primase domain and the helicase domain were structurally analyzed via a combination of small-angle X-ray scattering and, when appropriate, electron microscopy, leading to consistent low-resolution models of the different proteins.IMPORTANCESince the beginning of the 1980s, research on the vaccinia virus replication mechanism has basically stalled due to the absence of structural information. As a result, this important class of pathogens is less well understood than most other viruses. This lack of information concerns in general viruses of the NCLDV clade, which use a superfamily 3 helicase for replication, as do poxviruses. Here we provide for the first time information about the domain structure and DNA-binding activity of D5, the poxvirus helicase-primase. This result not only refines the current model of the poxvirus replication fork but also will lead in the long run to a structural basis for antiviral drug design.

scholarly journals SufR, a [4Fe-4S] Cluster-Containing Transcription Factor, Represses the sufRBDCSU Operon in Streptomyces avermitilis Iron-Sulfur Cluster Assembly

2020 ◽  
Vol 86 (18) ◽  
Author(s):  
Yaqing Cheng ◽  
Mengya Lyu ◽  
Renjun Yang ◽  
Ying Wen ◽  
Yuan Song ◽  
...  
Keyword(s):  
Dna Binding ◽  
Promoter Region ◽  
Binding Activity ◽  
Streptomyces Avermitilis ◽  
Assembly System ◽  
Cluster Assembly ◽  
Mobility Shift ◽  
Content Type ◽  
Dna Binding Activity ◽  
Iron Sulfur

ABSTRACT Iron-sulfur (Fe-S) clusters are ubiquitous and versatile inorganic cofactors that are crucial for many fundamental bioprocesses in nearly all organisms. How cells maintain Fe-S cluster homeostasis is not well understood in Gram-positive bacteria. Genomic analysis showed that the Suf system, which is encoded by the sufRBDCSU operon, is the sole Fe-S cluster assembly system in the genus Streptomyces. Streptomyces avermitilis is the industrial producer of avermectins, which are widely used as agricultural pesticides and antiparasitic agents. sufR (SAV6324) encodes a putative ArsR-family transcriptional regulator, which was characterized as a repressor of the sufRBDCSU operon in this investigation. Spectroscopy and mass spectrometry demonstrated that anaerobically isolated SufR contained an oxidation-sensitive [4Fe-4S] cluster and existed as a homodimer. Electrophoretic mobility shift assays (EMSAs) and DNase I footprinting analyses revealed that [4Fe-4S]-SufR bound specifically and tightly to a 14-bp palindromic sequence (CAAC-N6-GTTG) in the promoter region of the sufR operon, repressing expression of the sufRBDCSU operon. The presence of the [4Fe-4S] cluster is critical for the DNA-binding activity of SufR. Cys182, Cys195, and Cys223 in the C-terminal region of SufR are essential for [4Fe-4S] cluster coordination, but Cys178 is not. The fourth non-Cys ligand in coordination of the [4Fe-4S] cluster for SufR remains to be identified. The findings clarify the transcriptional control of the suf operon by [4Fe-4S] SufR to satisfy the various Fe-S cluster demands. SufR senses the intracellular Fe-S cluster status and modulates the expression of the sole Fe-S cluster assembly system via its Fe-S cluster occupancy. IMPORTANCE Fe–S clusters function as cofactors of proteins controlling diverse biological processes, such as respiration, photosynthesis, nitrogen fixation, DNA replication, and gene regulation. The mechanism of how Actinobacteria regulate the expression of the sole Fe-S cluster assembly system in response to the various Fe–S cluster demands remains to be elucidated. In this study, we showed that SufR functions as a transcriptional repressor of the sole Fe-S cluster assembly system in the avermectin producer S. avermitilis. [4Fe-4S]-SufR binds to the promoter region of the suf operon and represses its expression. When Fe-S cluster levels are insufficient, SufR loses its [4Fe-4S] cluster and DNA-binding activity. Apo-SufR dissociates from the promoter region of suf operon, and the expression of the suf system is strongly increased by derepression to promote the synthesis of Fe-S clusters. The study clarifies how Streptomyces maintains its Fe-S cluster homeostasis through the activity of SufR to modulate the various Fe-S cluster demands.

scholarly journals Identification of Extracellular DNA-Binding Proteins in the Biofilm Matrix

mBio ◽  
2019 ◽  
Vol 10 (3) ◽  
Author(s):  
Jeffrey S. Kavanaugh ◽  
Caralyn E. Flack ◽  
Jessica Lister ◽  
Erica B. Ricker ◽  
Carolyn B. Ibberson ◽  
...  
Keyword(s):  
Dna Binding ◽  
Cell Surface ◽  
Bacterial Cell ◽  
Binding Activity ◽  
Extracellular Dna ◽  
Bacterial Biofilms ◽  
Content Type ◽  
Bacterial Cell Surface ◽  
Dna Binding Activity ◽  
Biofilm Matrix

ABSTRACT We developed a new approach that couples Southwestern blotting and mass spectrometry to discover proteins that bind extracellular DNA (eDNA) in bacterial biofilms. Using Staphylococcus aureus as a model pathogen, we identified proteins with known DNA-binding activity and uncovered a series of lipoproteins with previously unrecognized DNA-binding activity. We demonstrated that expression of these lipoproteins results in an eDNA-dependent biofilm enhancement. Additionally, we found that while deletion of lipoproteins had a minimal impact on biofilm accumulation, these lipoprotein mutations increased biofilm porosity, suggesting that lipoproteins and their associated interactions contribute to biofilm structure. For one of the lipoproteins, SaeP, we showed that the biofilm phenotype requires the lipoprotein to be anchored to the outside of the cellular membrane, and we further showed that increased SaeP expression correlates with more retention of high-molecular-weight DNA on the bacterial cell surface. SaeP is a known auxiliary protein of the SaeRS system, and we also demonstrated that the levels of SaeP correlate with nuclease production, which can further impact biofilm development. It has been reported that S. aureus biofilms are stabilized by positively charged cytoplasmic proteins that are released into the extracellular environment, where they make favorable electrostatic interactions with the negatively charged cell surface and eDNA. In this work we extend this electrostatic net model to include secreted eDNA-binding proteins and membrane-attached lipoproteins that can function as anchor points between eDNA in the biofilm matrix and the bacterial cell surface. IMPORTANCE Many bacteria are capable of forming biofilms encased in a matrix of self-produced extracellular polymeric substances (EPS) that protects them from chemotherapies and the host defenses. As a result of these inherent resistance mechanisms, bacterial biofilms are extremely difficult to eradicate and are associated with chronic wounds, orthopedic and surgical wound infections, and invasive infections, such as infective endocarditis and osteomyelitis. It is therefore important to understand the nature of the interactions between the bacterial cell surface and EPS that stabilize biofilms. Extracellular DNA (eDNA) has been recognized as an EPS constituent for many bacterial species and has been shown to be important in promoting biofilm formation. Using Staphylococcus aureus biofilms, we show that membrane-attached lipoproteins can interact with the eDNA in the biofilm matrix and promote biofilm formation, which suggests that lipoproteins are potential targets for novel therapies aimed at disrupting bacterial biofilms.

scholarly journals The Conserved DNA Binding Protein WhiA Influences Chromosome Segregation inBacillus subtilis

2018 ◽  
Vol 200 (8) ◽  
Author(s):  
Laura C. Bohorquez ◽  
Katarina Surdova ◽  
Martijs J. Jonker ◽  
Leendert W. Hamoen
Keyword(s):  
Cell Division ◽  
Dna Binding ◽  
Chromosome Segregation ◽  
Nuclease Activity ◽  
Binding Activity ◽  
Homing Endonucleases ◽  
Content Type ◽  
Synthetic Lethal ◽  
Gram Positive Bacteria ◽  
Dna Binding Activity

ABSTRACTThe DNA binding protein WhiA is conserved in Gram-positive bacteria and is present in the genetically simple cell wall-lacking mycoplasmas. The protein shows homology to eukaryotic homing endonucleases but lacks nuclease activity. WhiA was first characterized in streptomycetes, where it regulates the expression of key differentiation genes, including the cell division geneftsZ, which is essential for sporulation. ForBacillus subtilis, it was shown that WhiA is essential when certain cell division genes are deleted. However, inB. subtilis, WhiA is not required for sporulation, and it does not seem to function as a transcription factor, despite its DNA binding activity. The exact function ofB. subtilisWhiA remains elusive. We noticed thatwhiAmutants show an increased space between their nucleoids, and here, we describe the results of fluorescence microscopy, genetic, and transcriptional experiments to further investigate this phenomenon. It appeared that the deletion ofwhiAis synthetic lethal when either the DNA replication and segregation regulator ParB or the DNA replication inhibitor YabA is absent. However, WhiA does not seem to affect replication initiation. We found that a ΔwhiAmutant is highly sensitive for DNA-damaging agents. Further tests revealed that the deletion ofparABinduces the SOS response, including the cell division inhibitor YneA. WhenyneAwas inactivated, the viability of the synthetic lethal ΔwhiAΔparABmutant was restored. However, the nucleoid segregation phenotype remained. These findings underline the importance of WhiA for cell division and indicate that the protein also plays a role in DNA segregation.IMPORTANCEThe conserved WhiA protein family can be found in most Gram-positive bacteria, including the genetically simple cell wall-lacking mycoplasmas, and these proteins play a role in cell division. WhiA has some homology with eukaryotic homing endonucleases but lacks nuclease activity. Because of its DNA binding activity, it is assumed that the protein functions as a transcription factor, but this is not the case in the model systemB. subtilis. The function of this protein inB. subtilisremains unclear. We noticed that awhiAmutant has a mild chromosome segregation defect. Further studies of this phenomenon provided new support for a functional role of WhiA in cell division and indicated that the protein is required for normal chromosome segregation.

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