Functional of Rng2p through reverse genetics

Master'sMASTER OF SCIENC

IQGAP-Related Rng2p Organizes Cortical Nodes and Ensures Position of Cell Division in Fission Yeast

SummaryCorrect positioning of the cell division machinery is crucial for genomic stability and cell fate determination. The fission yeast Schizosaccharomyces pombe, like animal cells, divides using an actomyosin ring and is an attractive model to study eukaryotic cytokinesis. In S. pombe, positioning of the actomyosin ring depends on the anillin-related protein Mid1p [1–3]. Mid1p arrives first at the medial cortex and recruits actomyosin ring components to node-like structures [4–7], although how this is achieved is unknown. Here we show that the IQGAP-related protein Rng2p, an essential component of the actomyosin ring [8, 9], is a key element downstream of Mid1p. Rng2p physically interacts with Mid1p and is required for the organization of other actomyosin ring components into cortical nodes. Failure of localization of Rng2p to the nodes prevents medial retention of Mid1p and leads to actomyosin ring assembly in a node-independent manner at nonmedial locations. We conclude that Mid1p recruits Rng2p to cortical nodes at the division site and that Rng2p, in turn, recruits other components of the actomyosin ring to cortical nodes, thereby ensuring correct placement of the division site

Bacterial diversity and bioprospecting for cold-active enzymes from culturable bacteria associated with sediment from a melt water stream of Midtre Lo<SUB>v<SUP>·</SUP></SUB>enbreen glacier, an Arctic glacier

Culturable bacterial diversity of Midtre Loenbreen glacier, an Arctic glacier, was studied using 12 sediment samples collected from different points, along a transect, from the snout of Midtre Lov·enbreen glacier up to the convergence point of the melt water stream with the sea. Bacterial abundance appeared to be closer to the convergence point of the glacial melt water stream with the sea than at the snout of the glacier. A total of 117 bacterial strains were isolated from the sediment samples. Based on 16S rRNA gene sequence analyses, the isolates (n = 117) could be categorised in to 32 groups, with each group representing a different taxa belonging to 4 phyla (Actinobacteria, Bacilli, Flavobacteria and Proteobacteria). Representatives of the 32 groups varied in their growth temperature range (4-37 °C), in their tolerance to NaCl (0.1-1 M NaCl) and in the growth pH range (2-13). Only 14 of 32 representative strains exhibited amylase, lipase and (or) protease activity and only one isolate (AsdM4-6) showed all three enzyme activities at 5 and 20 °C respectively. More than half of the isolates were pigmented. Fatty acid profile studies indicated that short-chain fatty acids, unsaturated fatty acids, branched fatty acids, cyclic and cis fatty acids are predominant in the psychrophilic bacteria

The m-AAA Protease Associated with Neurodegeneration Limits MCU Activity in Mitochondria

Mutations in subunits of mitochondrialm-AAA proteases in the inner membrane cause neurodegeneration in spinocerebellar ataxia (SCA28) and hereditary spastic paraplegia (HSP7). m-AAA proteases preserve mitochondrial proteostasis, mitochondrial morphology, and efficient OXPHOS activity, but the cause for neuronal loss in disease is unknown. We have determined the neuronal interactome of m-AAA proteases in mice and identified a complex with C2ORF47 (termed MAIP1), which counteracts cell death by regulating the assembly of the mitochondrial Ca2+ uniporter MCU. While MAIP1 assists biogenesis of the MCU subunit EMRE, the m-AAA protease degrades non-assembled EMRE and ensures efficient assembly of gatekeeper subunits with MCU. Loss of the m-AAA protease results in accumulation of constitutively active MCU-EMRE channels lacking gatekeeper subunits in neuronal mitochondria and facilitates mitochondrial Ca2+ overload, mitochondrial permeability transition pore opening, and neuronal death. Together, our results explain neuronal loss in m-AAA protease deficiency by deregulated mitochondrial Ca2+ homeostasis