Biology subjects

Heindl, J. E.

Publications and source records attributed to Heindl, J. E..

3 recordsLinked to original sources

bioRxiv2026

A FeuP-FeuQ-Dependent Regulatory Module Integrating Envelope Stress and Host-Associated Behaviors in Agrobacterium tumefaciens

Agrobacterium tumefaciens is an important plant pathogen, the causative agent of crown gall disease, and a foundational technology used for genetic transformation of plant tissue. More recently, A. tumefaciens has been adopted as a genetically tractable model organism for studying bacterial cell cycle regulation, developmental pathways, and niche construction. The transition from a free-living bacterium within the rhizosphere to association with a plant host and subsequent transformation of plant tissue is one aspect of A. tumefaciens life history that encompasses all three of these processes. Such events are coordinated by multiple regulatory modules which must sense external and/or internal cues, integrate these inputs, and effect appropriate changes in gene expression and cellular responses to maximize fitness. Here, we evaluate the contribution of the two-component system, FeuP-FeuQ, to gene expression and developmental phenotypes including surface attachment/biofilm formation, swimming motility, and tumorigenesis. feuPQ operon organization suggests translational coupling during expression of the response regulator, FeuP (Atu0970), and sensor kinase, FeuQ (Atu0971). In-frame, non-polar deletion of feuP or feuQ individually, or the entire feuPQ operon, resulted in reduced biofilm formation, swimming motility, and tumor formation, without adversely affecting planktonic growth. Transcriptomic profiling identified [~]300 differentially expressed genes when the feuPQ locus was disrupted, including genes affecting flagellar motility, succinoglycan production, and type VI secretion. Phenotype profiling emphasized the contribution of feuPQ to withstanding osmotic, ionic, and antimicrobial stressors. Together, these data highlight FeuPQ as a global regulator of cellular responses which likely contribute to overall fitness during rhizosphere lifestyle transitions. IMPORTANCEAgrobacterium tumefaciens is an important plant pathogen able to genetically transform numerous plant species. In the rhizosphere, this bacterium encounters many challenges ranging from antagonistic and competing microbes, to plant host defenses, to rapidly changing environmental conditions. Efficient host interaction leading to plant transformation requires coordination of bacterial motility, attachment, and defense mechanisms, among other processes. This work identifies two proteins, FeuP and FeuQ, that together contribute to such coordination. The importance of this work is in identifying the FeuPQ system as a global regulator of these and other processes, possibly enabling targeted interventions to promote or inhibit plant transformation.

microbiology↗

bioRxiv2025

Analyzing the role of a dual-function diguanylate cyclase/phosphodiesterase for attachment and motility in Agrobacterium tumefaciens

Cyclic diguanylate monophosphate (c-di-GMP) is a second messenger that controls the signaling pathway for the motile to sessile transition in many bacteria. Diguanylate cyclases (DGCs), characterized by a GGDEF domain, are responsible for the synthesis of c-di-GMP. c-di-GMP is degraded by EAL and HD-GYP domains that exhibit phosphodiesterase activity (PDE). In Agrobacterium tumefaciens, out of 31 predicted proteins regulating the c-di-GMP levels, this work focuses on the predicted dual-function DGC/PDE, DcpB. We show that DcpB is a cycle-dependent PDE under our experimental conditions, resulting in cell cycle-dependent control of motility and biofilm formation in A. tumefaciens. DcpB also exhibits polar and mid-cell localization. Finally, we identify genetic interactions between dcpB and a LacI-family transcriptional regulators, thuR, suggesting additional regulatory inputs for DcpB-dependent phenotypes. Importancec-di-GMP is a universal secondary messenger known to control various biological processes in bacteria including attachment, motility, virulence, and cell cycle progression. In A. tumefaciens, there are 31 predicted c-di-GMP-metabolizing proteins predicted to affect the c-di-GMP pool, raising the question of why so many proteins are involved and how the activities of these proteins are coordinated. This work describes a cell cycle-dependent PDE activity that helps coordinate cell cycle progression and developmental phenotypes including biofilm formation and motility.

microbiology↗

bioRxiv2017

Reciprocal control of motility and biofilm formation by the PdhS2 two-component sensor kinase of Agrobacterium tumefaciens

A core regulatory pathway that directs developmental transitions and cellular asymmetries in Agrobacterium tumefaciens involves two overlapping, integrated phosphorelays. One of these phosphorelays putatively includes four histidine sensor kinase homologues, DivJ, PleC, PdhS1, and PdhS2, and two response regulators, DivK and PleD. In several different alphaproteobacteria, this pathway influences a conserved downstream phosphorelay that ultimately controls the phosphorylation state of the CtrA master response regulator. The PdhS2 sensor kinase reciprocally regulates biofilm formation and swimming motility. In the current study the mechanisms by which the A. tumefaciens sensor kinase PdhS2 directs this regulation are delineated. PdhS2 lacking a key residue for phosphatase activity is markedly deficient in proper control of attachment and motility phenotypes, whereas a kinase-deficient PdhS2 mutant is only modestly affected. A genetic interaction between DivK and PdhS2 is revealed, unmasking one of several connections between PdhS2-dependent phenotypes and transcriptional control by CtrA. Epistasis experiments suggest that PdhS2 can function independently of the CckA sensor kinase, the cognate sensor kinase for CtrA which is inhibited by DivK. PdhS2 dynamically localizes to the daughter cell pole in dividing cells. Global expression analysis of the pdhS2 mutant reveals a restricted regulon, functioning through CtrA to separately control motility and regulate levels of the intracellular signal cyclic diguanylate monophosphate (cdGMP), thereby affecting production of adhesive polysaccharides and attachment. We hypothesize that in A. tumefaciens the CtrA regulatory circuit has expanded to include additional inputs through addition of PdhS-type sensor kinases, likely fine-tuning the response of this organism to the soil microenvironment.\n\nIMPORTANCEBacterial developmental processes, such as morphological transformations and behavioral transitions, are tightly regulated. In many alphaproteobacteria cell division and development are coordinated by a specific suite of conserved histidine kinases and their partnered regulatory proteins. Here we describe how the histidine kinase PdhS2 of Agrobacterium tumefaciens regulates complex phenotypes including biofilm formation and motility. PdhS2 genetically interacts with a single-domain response regulator, DivK, and the intracellular signal cyclic diguanylate monophosphate. PdhS2 dynamically localizes to the new pole of recently divided cells, contributing to the regulatory processes that dictate whether these cells remain motile or initiate biofilm formation. These findings expand our understanding of the complex network that integrates cell division and developmental control in A. tumefaciens and related alphaproteobacteria.

microbiology↗