Dataset Information

Proteomics characterization of the inner membrane domain (IMD) from Mycobacterium tuberculosis

ABSTRACT: The inner membrane domain (IMD) is a metabolically active and laterally discrete membrane domain initially discovered in Mycobacterium smegmatis that correlates both temporally and spatially with polar cell envelope elongation. While it has remained unclear whether a similar membrane domain exists in pathogenic species, this study specifically demonstrates that the IMD is a conserved membrane structure found in Mycobacterium tuberculosis. Following isolation of the membrane domains by density gradient fractionation, proteomic analysis revealed that the IMD is enriched in metabolic enzymes that are involved in the synthesis of conserved cell envelope components such as peptidoglycan, arabinogalactan, and phosphatidylinositol mannosides. Further, by demonstrating that the IMD is concentrated in the polar region of the rod-shaped cells, where active cell envelope biosynthesis takes place, proteomic analysis further revealed the enrichment of enzymes involved in synthesis of phthiocerol dimycocerosates and phenolic glycolipids. Overall, these proteomic data support that the functional compartmentalization of the membrane is an evolutionarily conserved feature found in both M. tuberculosis and M. smegmatis.

INSTRUMENT(S):

ORGANISM(S): Mycobacterium Tuberculosis Tbr27

TISSUE(S): Prokaryotic Cell, Cell Culture

DISEASE(S): Tuberculosis

SUBMITTER: Scott Shaffer

LAB HEAD: Yasu S. Morita

PROVIDER: PXD069609 | Pride | 2025-11-21

REPOSITORIES: Pride

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Dataset's files

Source:

			Action	DRS
	042717MoritaSample1.msf	Msf
	042717MoritaSample1.mzid	Mzid
	042717MoritaSample1.mzid_042717MoritaSample1.MGF	Mzid
	042717MoritaSample1.raw	Raw
	042717MoritaSample2.msf	Msf

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Project description:CarD is an essential mycobacterial protein that we had previously shown to bind the RNA polymerase (RNAP) and affect the transcriptional profile of M. smegmatis and Mycobacterium tuberculosis. For this reason, we suspected that CarD was directly regulating transcriptional complexes but we did not know at what stage of CarD was functioning and at which genes CarD interacted with the RNAP. To determine in which stage of the transcription cycle (initiation, elongation, or termination) CarD acts, we used Chromatin Immunoprecipitation sequencing (ChIP-seq) to survey the distribution of CarD throughout the M. smegmatis chromosome. Specific antibodies targeting core RNAPb, RNAPσ, or a hemagglutinin (HA) epitope fused to CarD (CarD-HA) were used to co-immunoprecipitate associated DNA. CarD-HA was immunoprecipitated from the M. smegmatis Mc2155 ΔcarD attB::tetcarD-HA strain and unfused HA was immunoprecipitated from the Mc2155 attB::pmsg431 strain with monoclonal antibodies specific for HA (Sigma). RNAP β and σ were immunoprecipitated from M. smegmatis ΔcarD attB::tetcarD-HA with monoclonal antibodies specific for these subunits (Neoclone, Madison, WI; 8RB13 for β, 2G10 for σ). Co-precipitated DNA was sequenced using a SOLiD sequencer (Life Technologies), which provided sufficient reads for 100-fold coverage of the genome. The number of sequence reads per base pair was normalized to the total number of reads and expressed as a log2 value. The reads per base pair from the HA-alone sample served as the background and was subtracted from the other datasets. We found that CarD was never present on the genome in the absence of RNAP. However, whereas RNAP core enzyme was found throughout transcribed regions of the genome, CarD was primarily associated with promoter regions and highly correlated with RNAPσ. The colocalization of σA and CarD led us to propose that in vivo, CarD associates with RNAP initiation complexes at most promoters and is therefore a global regulator of transcription initiation. The genome sequences associated with M. smegmatis CarD, RNAPb, and RNAPs were determined by ChIP-seq analysis. Samples were done in duplicate, except for RNAPs. And sequencing was performed using a SOLiD sequencer (Life Technologies).

Project description:Î³-secretase is an intra-membrane-cleaving aspartyl protease implicated in the processing of a wide range of type I membrane proteins including the Notch receptor and the amyloid-Î² precursor protein (APP). It thus regulates a diverse array of cellular and biological processes including the differentiation of neuronal embryonic stem cells, or intestinal stem cells, with the latter controlling the self-renewing of the intestinal epithelium. Indeed, proteolysis of these proteins by Î³-secretase triggers signaling cascades by releasing intracellular domains (ICDs) which, following association with adaptor proteins and nuclear translocation, modulate the transcription of different genes by binding directly to their promoters. The pronounced proliferative and regenerative effects of Notch signaling and its implication in the generation of the AÎ²-peptides, makes Î³-secretase a therapeutic target for several types of cancer and for Alzheimerâs disease. To investigate the broad effects of Î³-secretase activity onto the cellular transcriptome, Chinese hamster ovary (CHO) cells with enhanced Î³-secretase were compared to cells with abolished Î³-secretase activity via a microarray designed for a genetically close species, mouse. Our findings will potentially help to decipher the biology of Î³-secretase, including a better understanding of the roles of this enzyme in gene transcription. We compared the transcriptomes of two CHO cell lines displaying extreme differences in Î³-secretase activity. The S-1 cell line overexpressed the four components of Î³-secretase (NCT, APH1aL, PS1, and PEN2) and was characterized by a marked increase in the level of PS1 heterodimers associated with 8-fold increased Î³-secretase activity compared to untransfected controls. The other cell line consisted of wild type CHO cells incubated with DAPT, a well-known Î³-secretase inhibitor. The two cell lines were used in combination with a mouse microarray to analyze gene transcription under enhanced Î³-secretase. Two samples, S1 and DAPT treated CHO- were used in biological triplicates each.

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Proteomics characterization of the inner membrane domain (IMD) from Mycobacterium tuberculosis

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