Biology subjects

Grana, M.

Publications and source records attributed to Grana, M..

5 recordsLinked to original sources

bioRxiv2021

Archaeal origins of gamete fusion

Sexual reproduction consists of genome reduction by meiosis and subsequent gamete fusion. Presence of meiotic genes in prokaryotes suggests that DNA repair mechanisms evolved toward meiotic recombination; however, fusogenic proteins resembling those found in eukaryotes were not identified in prokaryotes. Here, we identify archaeal proteins that are homologs of fusexins, a superfamily of fusogens that mediate eukaryotic gamete and somatic cell fusion, as well as virus entry. The crystal structure of a trimeric archaeal Fusexin1 reveals novel features such as a six-helix bundle and an additional globular domain. Ectopically expressed Fusexin1 can fuse mammalian cells, and this process involves the additional domain and a conserved fusion loop. Archaeal fusexin genes exist within integrated mobile elements, potentially linking ancient archaeal gene exchanges and eukaryotic sex. One-Sentence SummaryCell membrane fusion proteins of viruses and eukaryotes are also present in archaea.

evolutionary biology↗

bioRxiv2021

A TPR scaffold couples signal detection to OdhI phosphorylation in metabolic control by the protein kinase PknG

Signal transduction is essential for bacteria to adapt to changing environmental conditions. Among many forms of post-translational modifications, reversible protein phosphorylation has evolved as a ubiquitous molecular mechanism of protein regulation in response to specific stimuli. The Ser/Thr protein kinase PknG modulates the fate of intracellular glutamate by controlling the phosphorylation status of the 2-oxoglutarate dehydrogenase regulator OdhI, a function that is conserved among diverse actinobacteria. PknG has a modular organization characterized by the presence of regulatory domains surrounding the catalytic domain. Here we present an investigation through in vivo experiments as well as biochemical and structural methods of the molecular bases of the regulation of PknG from C. glutamicum (CgPknG), in the light of previous knowledge available for the kinase from M. tuberculosis (MtbPknG). We found that OdhI phosphorylation by CgPknG is regulated by a conserved mechanism that depends on a C-terminal domain composed of tetratricopeptide repeats (TPR) essential for metabolic homeostasis. Furthermore, we identified a conserved structural motif that physically connects the TPR domain and a flexible N-terminal extension of the kinase that is involved in docking interactions with OdhI. Based on our results and previous reports, we propose a model in which the TPR domain of PknG couples signal detection to the specific phosphorylation of OdhI. Overall, the available data indicate that conserved PknG domains in distant actinobacteria retain their roles in kinase regulation in response to nutrient availability. IMPORTANCEBacteria control the metabolic processes by which they obtain nutrients and energy in order to adapt to the environment. In this way, the metabolic characteristics of a microorganism determine its ecological role and its usefulness in industrial processes. Here, we use genetic, biochemical, and structural approaches to study a key component in a system that regulates glutamate production in C. glutamicum, a species that is used for the industrial production of amino acids. We elucidated molecular mechanisms involved in metabolic control in C. glutamicum, which are conserved in related pathogenic bacteria. The findings have broader significance for diverse actinobacteria, including microorganisms that cause disease as well as environmental species used to produce billions of dollars of amino acids and antibiotics every year.

biochemistry↗

bioRxiv2020

Detecting fine and elaborate movements with piezo sensors, from heartbeat to the temporal organization of behavior

Behavioral phenotyping devices have been successfully used to build ethograms, but studying the temporal dynamics of individual movements during spontaneous, ongoing behavior, remains a challenge. We now report on a novel device, the Phenotypix, which consists in an open-field platform resting on highly sensitive piezoelectric (electro-mechanical) pressure-sensors, with which we could detect the slightest movements from freely moving rats and mice. The combination with video recordings and signal analysis based on time-frequency decomposition, clustering and machine learning algorithms allowed to quantify various behavioral components with unprecedented accuracy, such as individual heartbeats and breathing cycles during rest, shaking in response to pain or fear, and the dynamics of balance within individual footsteps during spontaneous locomotion. We believe that this device represents a significant progress and offers new opportunities for the awaited advance of behavioral phenotyping.

animal behavior and cognition↗

bioRxiv2019

Essential dynamic interdependence of FtsZ and SepF for Z-ring and septum formation in Corynebacterium glutamicum

The mechanisms of Z-ring assembly and regulation in bacteria are poorly understood, particularly in non-model organisms. Actinobacteria, one of the largest bacterial phyla that includes the deadly human pathogen Mycobacterium tuberculosis, lack the canonical FtsZ-membrane anchors as well as all positive and negative Z-ring regulators described for E. coli. Here we investigate the physiological function of Corynebacterium glutamicum SepF, the only cell division-associated protein from Actinobacteria known to directly interact with the conserved C-terminal tail of FtsZ but whose actual mode of action in cytokinesis is yet to be elucidated. We used a mechanistic cell biology approach to unveil the essential interdependence of FtsZ and SepF required for the formation of a functional Z-ring in the actinobacterial model organism C. glutamicum. The crystal structure of the SepF-FtsZ complex reveals a hydrophobic FtsZ-binding pocket, which defines the SepF homodimer as the functional unit, and a reversible oligomerization interface regulated via an alpha helical switch. FtsZ filaments and lipid membranes have opposing effects on SepF polymerization, leading to a complex dynamic role of the protein at the division site, involving FtsZ bundling, Z-ring tethering and membrane reshaping activities that are needed for proper Z-ring assembly and function.

microbiology↗

bioRxiv2016

Arabidopsis HAP2/GCS1 is a gamete fusion protein homologous to somatic and viral fusogens

Cell-cell fusion is inherent to any form of sexual reproduction. Loss of HAPLESS 2/GENERATIVE CELL SPECIFIC 1 (HAP2/GCS1) proteins results in gamete fusion failure in different organisms but their exact role is unclear. Here we show that Arabidopsis HAP2/GCS1 expression in mammalian cells is sufficient to promote cell-cell fusion. Hemifusion and complete fusion depend on HAP2/GCS1 presence in both fusing cells. Furthermore, expression of HAP2 on the surface of pseudotyped vesicular stomatitis virus and on the target cells results in HAP2-dependent virus-cell fusion. This bilateral requirement can be bypassed by replacing the plant gene with C. elegans EFF-1 somatic cell fusogen in one of the fusing cells or the virus, indicating that HAP2/GCS1 and EFF-1 share a similar fusion mechanism. Structural modeling of the HAP2/GCS1 protein family predicts that they are homologous to EFF-1 and class II fusion proteins from enveloped viruses (e.g. dengue and Zika viruses). We name this superfamily FUSEXINS: FUSion proteins essential for sexual reproduction and EXoplasmic merger of plasma membranes. Thus, Fusexins unify the origin and evolution of sexual reproduction, enveloped virus entry into cells and somatic cell fusion.

cell biology↗