| 1. |
- Bagchi, Sonchita, 1978-
(författare)
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Coiled coil Cytoskeleton in Bacterial Cell Architecture : Studies of Growth and Development in Streptomyces
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Bacterial cytoskeleton is an exciting and relatively new field of research. Recent findings have proven that microbes are well-organized and neatly structured organisms. In this study we have shown that intermediate filament-like proteins with a characteristic rod domain architecture of coiled coil segments separated by non-coiled coil linkers, are widely spread among bacteria. We identified and characterized an intermediate filament-like protein (named FilP after filamentous protein) in Streptomyces coelicolor. It shares the characteristic biochemical property of eukaryotic intermediate filaments of formation of spontaneous filaments in vitro without requiring any energy or co-factor. We have provided here a preliminary model of its assembly in vitro. FilP also forms in vivo filaments in S. coelicolor hyphae, which are strongest at the sub-apical location of growing vegetative hyphae. We have proposed that FilP cytoskeletal network provides rigidity to the hyphae, especially at the growing tips, by interacting with an essential coiled coil protein DivIVA and possibly other partner elements, yet to be found. S. coelicolor is a well-studied model organism with a complicated life cycle. It germinates from a spore and spreads by forming branched vegetative hyphae. Lack of nutrients in the environment initiates formation of aerial hyphae in the air, perpendicular to the vegetative ones. The aerial hyphae differentiate into spore chains and eventually grey-pigmented dispersed individual spores are released. The signals involved in sporulation including cell division and chromosome segregation are not clear yet. We characterized here a novel locus consisting of two genes: a small putative membrane protein with no defined function, named SmeA and a member of the SpoIIIE/FtsK family, called SffA. The expression of this locus appears to be dependent on whiA and whiG-whiH-whiI pathways. This finding is intriguing as it can provide insight to the relationship between two apparently unrelated pathways, both leading to the same function of septation and maturation during sporulation.
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| 2. |
- Bagchi, Sonchita, 1978-, et al.
(författare)
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Probable role for major facilitator superfamily domain containing 6 (MFSD6) in the brain during variable energy consumption
- 2020
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Ingår i: International Journal of Neuroscience. - : Informa UK Limited. - 0020-7454 .- 1563-5279 .- 1543-5245. ; 130:5, s. 476-489
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The major facilitator superfamily (MFS) is known as the largest and most diverse superfamily containing human transporters, and these transporters are essential as they sustain the homeostasis within cellular compartments by moving substances over lipid membranes.Methods: We have identified a novel MFS protein, named Major facilitator superfamily domain containing 6 (MFSD6), and confirmed that it is phylogenetically related to the human Solute Carrier (SLC) transporter family. A homology model of MFSD6 revealed 12 predicted transmembrane segments (TMS) with the classical MFS fold between TMS 6 and 7.Results: Immunohistological analyses showed specific MFSD6 staining in neurons of wildtype mouse brain tissue, but no expression in astrocytes. Furthermore, we explored expression and probable function(s) of MFSD6 in relation to its phylogenetically related proteins, major facilitator superfamily domain containing 8 (MFSD8) and 10 (MFSD10), which is of interest as both these proteins are involved in diseases.Conclusions: We showed that expression levels of Mfsd6 and Mfsd10 were decreased with elevated or depleted energy consumption, while that of Mfsd8 remained unaffected.
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| 3. |
- Gandasi, Nikhil, et al.
(författare)
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Glutamine Uptake via SNAT6 and Caveolin Regulates Glutamine-Glutamate Cycle
- 2021
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Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1422-0067 .- 1661-6596. ; 22:3
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Tidskriftsartikel (refereegranskat)abstract
- SLC38A6 (SNAT6) is the only known member of the SLC38 family that is expressed exclusively in the excitatory neurons of the brain. It has been described as an orphan transporter with an unknown substrate profile, therefore very little is known about SNAT6. In this study, we addressed the substrate specificity, mechanisms for internalization of SNAT6, and the regulatory role of SNAT6 with specific insights into the glutamate-glutamine cycle. We used tritium-labeled amino acids in order to demonstrate that SNAT6 is functioning as a glutamine and glutamate transporter. SNAT6 revealed seven predicted transmembrane segments in a homology model and was localized to caveolin rich sites at the plasma membrane. SNAT6 has high degree of specificity for glutamine and glutamate. Presence of these substrates enables formation of SNAT6-caveolin complexes that aids in sodium dependent trafficking of SNAT6 off the plasma membrane. To further understand its mode of action, several potential interacting partners of SNAT6 were identified using bioinformatics. Among them where CTP synthase 2 (CTPs2), phosphate activated glutaminase (Pag), and glutamate metabotropic receptor 2 (Grm2). Co-expression analysis, immunolabeling with co-localization analysis and proximity ligation assays of these three proteins with SNAT6 were performed to investigate possible interactions. SNAT6 can cycle between cytoplasm and plasma membrane depending on availability of substrates and interact with Pag, synaptophysin, CTPs2, and Grm2. Our data suggest a potential role of SNAT6 in glutamine uptake at the pre-synaptic terminal of excitatory neurons. We propose here a mechanistic model of SNAT6 trafficking that once internalized influences the glutamate-glutamine cycle in presence of its potential interacting partners.
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| 4. |
- Perland, Emelie, et al.
(författare)
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Characteristics of 29 novel atypical SLCs of MFS type : evolutionary conservation, predicted structure and neuronal co-expression
- 2017
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Ingår i: Open Biology. - : The Royal Society. - 2046-2441. ; 7:9
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Tidskriftsartikel (refereegranskat)abstract
- Solute carriers (SLCs) are vital as they are responsible for a major part of the molecular transport over lipid bilayers. At present, there are 430 identified SLCs, of which 28 are called atypical SLCs of major facilitator superfamily (MFS) type. These are MFSD1, 2A, 2B, 3, 4A, 4B, 5, 6, 6L, 7, 8, 9, 10, 11, 12, 13A, 14A, 14B; SV2A, SV2B, SV2C, SVOP, SVOPL; SPNS1, SPNS2, SPNS3; UNC93A and UNC93B1, and we studied their fundamental properties. We also included CLN3, an atypical SLC not yet belonging to any Pfam clan, because its involvement in the same neuronal degenerative disorders as MFSD8. With phylogenetic analyses and bioinformatic sequence comparisons, the proteins were divided into 15 families, denoted Atypical MFS Transporter Families (AMTF1-15). Hidden Markov models were used to identify orthologues from human to D.melanogaster and C.elegans. Topology predictions revealed 12 transmembrane segments (for all except CLN3), corresponding to the common MFS structure. With single-cell RNA sequencing and in situ proximity ligation assay on brain cells, co-expressions of several atypical SLC were identified. Finally, the transcription levels of all genes were analysed in the hypothalamic N25/2 cell line after complete amino acid starvation, showing altered expression levels for several atypical SLCs.
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| 5. |
- Tripathi, Rekha, et al.
(författare)
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SLC38A10 (SNAT10) is Located in ER and Golgi Compartments and Has a Role in Regulating Nascent Protein Synthesis.
- 2019
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Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 20:24
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Tidskriftsartikel (refereegranskat)abstract
- The solute carrier (SLC) family-38 of transporters has eleven members known to transport amino acids, with glutamine being a common substrate for ten of them, with SLC38A9 being the exception. In this study, we examine the subcellular localization of SNAT10 in several independent immortalized cell lines and stem cell-derived neurons. Co-localization studies confirmed the SNAT10 was specifically localized to secretory organelles. SNAT10 is expressed in both excitatory and inhibitory neurons in the mouse brain, predominantly in the endoplasmic reticulum, and in the Golgi apparatus. Knock-down experiments of SNAT10, using Slc38a10-specific siRNA in PC12 cells reduced nascent protein synthesis by more than 40%, suggesting that SNAT10 might play a role in signaling pathways that regulate protein synthesis, and may act as a transceptor in a similar fashion to what has been shown previously for SLC38A2 (SNAT2) and SNAT9(SLC38A9).
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