Marta Gomez Munoz

• Birhanu, Alemayehu Godana; Munoz, Marta Gomez; Kalayou, Shewit; Riaz, Tahira; Lutter, Timo & Yimer, Solomon Abebe [Show all 8 contributors for this article] (2022). Proteome Profiling of Mycobacterium tuberculosis Cells Exposed to Nitrosative Stress. ACS Omega. 7(4), p. 3470–3482. doi: 10.1021/acsomega.1c05923. Full text in Research Archive Show summary

  Reactive nitrogen species (RNS) are secreted by human cells in response to infection by Mycobacterium tuberculosis (Mtb). Although RNS can kill Mtb under some circumstances, Mtb can adapt and survive in the presence of RNS by a process that involves modulation of gene expression. Previous studies focused primarily on stress-related changes in the Mtb transcriptome. This study unveils changes in the Mtb proteome in response to a sub-lethal dose of nitric oxide (NO) over several hours of exposure. Proteins were identified using liquid chromatography coupled with electrospray ionization mass spectrometry (LC–MS/MS). A total of 2911 Mtb proteins were identified, of which 581 were differentially abundant (DA) after exposure to NO in at least one of the four time points (30 min, 2 h, 6 h, and 20 h). The proteomic response to NO was marked by two phases, with few DA proteins in the early phase and a multitude of DA proteins in the later phase. The efflux pump Rv1687 stood out as being the only protein more abundant at all the time points and might play a role in the early protection of Mtb against nitrosative stress. These changes appeared to be compensatory in nature, contributing to iron homeostasis, energy metabolism, and other stress responses. This study thereby provides new insights into the response of Mtb to NO at the level of proteomics.

• Hovland, Eirik; Beyene, Getachew Tesfaye; Frye, Stephan Alfons; Homberset, Håvard; Balasingham, Seetha & Munoz, Marta Gomez [Show all 9 contributors for this article] (2017). DprA from Neisseria meningitidis: properties and role in natural competence for transformation. Microbiology (Reading). ISSN 1350-0872. 163(7), p. 1016–1029. doi: 10.1099/mic.0.000489. Full text in Research Archive Show summary

  DNA processing chain A (DprA) is a DNA-binding protein that is ubiquitous in bacteria and expressed in some archaea. DprA is active in many bacterial species that are competent for transformation of DNA, but its role in Neisseriameningitidis (Nm) is not well characterized. An Nm mutant lacking DprA was constructed, and the phenotypes of the wild-type and ΔdprA mutant were compared. The salient feature of the phenotype of dprA null cells is the total lack of competence for genetic transformation shown by all of the donor DNA substrates tested in this study. Here, Nm wild-type and dprA null cells appeared to be equally resistant to genotoxic stress. The gene encoding DprANm was cloned and overexpressed, and the biological activities of DprANm were further investigated. DprANm binds ssDNA more strongly than dsDNA, but lacks DNA uptake sequence-specific DNA binding. DprANm dimerization and interaction with the C-terminal part of the single-stranded binding protein SSBNmwere demonstrated. dprA is co-expressed with smg, a downstream gene of unknown function, and the gene encoding topoisomerase 1, topA.

• Namouchi, Amine; Munoz, Marta Gomez; Frye, Stephan Alfons; Moen, Line Victoria; Rognes, Torbjørn & Tonjum, Tone [Show all 7 contributors for this article] (2016). The Mycobacterium tuberculosis transcriptional landscape under genotoxic stress. BMC Genomics. 17:791, p. 1–13. doi: 10.1186/s12864-016-3132-1. Full text in Research Archive Show summary

  Background: As an intracellular human pathogen, Mycobacterium tuberculosis (Mtb) is facing multiple stressful stimuli inside the macrophage and the granuloma. Understanding Mtb responses to stress is essential to identify new virulence factors and pathways that play a role in the survival of the tubercle bacillus. The main goal of this study was to map the regulatory networks of differentially expressed (DE) transcripts in Mtb upon various forms of genotoxic stress. We exposed Mtb cells to oxidative (H2O2 or paraquat), nitrosative (DETA/NO), or alkylation (MNNG) stress or mitomycin C, inducing double-strand breaks in the DNA. Total RNA was isolated from treated and untreated cells and subjected to high-throughput deep sequencing. The data generated was analysed to identify DE genes encoding mRNAs, non-coding RNAs (ncRNAs), and the genes potentially targeted by ncRNAs. Results: The most significant transcriptomic alteration with more than 700 DE genes was seen under nitrosative stress. In addition to genes that belong to the replication, recombination and repair (3R) group, mainly found under mitomycin C stress, we identified DE genes important for bacterial virulence and survival, such as genes of the type VII secretion system (T7SS) and the proline-glutamic acid/proline-proline-glutamic acid (PE/PPE) family. By predicting the structures of hypothetical proteins (HPs) encoded by DE genes, we found that some of these HPs might be involved in mycobacterial genome maintenance. We also applied a state-of-the-art method to predict potential target genes of the identified ncRNAs and found that some of these could regulate several genes that might be directly involved in the response to genotoxic stress. Conclusions: Our study reflects the complexity of the response of Mtb in handling genotoxic stress. In addition to genes involved in genome maintenance, other potential key players, such as the members of the T7SS and PE/PPE gene family, were identified. This plethora of responses is detected not only at the level of DE genes encoding mRNAs but also at the level of ncRNAs and their potential targets.

• Lillenes, Meryl Sønderby; Støen, Mari; Gómez-Muñoz, Marta; Torp, Reidun; Günther, Clara-Cecilie & Nilsson, Lars [Show all 7 contributors for this article] (2013). Transient OGG1, APE1, PARP1 and Polβ expression in an Alzheimer's disease mouse model. Mechanisms of Ageing and Development. ISSN 0047-6374. 134(10), p. 467–477. doi: 10.1016/j.mad.2013.09.002. Full text in Research Archive Show summary

  Alzheimer's disease (AD) is a disease of major public health significance, whose pathogenesis is strongly linked to the presence of fibrillar aggregates of amyloid-beta (Aβ) in the aging human brain. We exploited the transgenic (Tg)-ArcSwe mouse model for human AD to explore whether oxidative stress and the capacity to repair oxidative DNA damage via base excision repair (BER) are related to Aβ pathology in AD. Tg-ArcSwe mice express variants of Aβ, accumulating senile plaques at 4–6 months of age, and develop AD-like neuropathology as adult animals. The relative mRNA levels of genes encoding BER enzymes, including 8-oxoguanine glycosylase (OGG1), AP endonuclease 1 (APE1), polymerase β (Polβ) and poly(ADP-ribose) polymerase 1 (PARP1), were quantified in various brain regions of 6 weeks, 4 months and 12 months old mice. The results show that OGG1 transcriptional expression was higher, and APE1 expression lower, in 4 months old Tg-ArcSwe than in wildtype (wt) mice. Furthermore, Polβ transcriptional expression was significantly lower in transgenic 12 months old mice than in wt. Transcriptional profiling also showed that BER repair capacity vary during the lifespan in Tg-ArcSwe and wt mice. The BER expression pattern in Tg-ArcSwe mice thus reflects responses to oxidative stress in vulnerable brain structures.

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• Munoz, Marta Gomez; Namouchi, Amine; Balasingham, Seetha & Tonjum, Tone (2016). Identifiying ncRNAs expressed under genotoxic stress and dormancy in Mycobacterium tuberculosis. Full text in Research Archive Show summary

  Mycobacterium tuberculosis (Mtb) is the intracellular pathogen that causes tuberculosis (TB), an infectious disease responsible for 1.5 million deaths worldwide in 2015. This bacterium is inhaled in aerosol droplets and once in the lung, it is engulfed by alveolar macrophages. Inside the activated macrophage, Mtb is exposed to a hostile environment, including reactive oxygen species (ROS) and reactive nitrogen species (RNS) that cause oxidation, deamination and alkylation of macromolecules. This condition is fatal to most bacterial pathogens, but Mtb has the ability to sense the host environment and eventually enter into a non-replicating, persistent state. The tubercle bacilli can remain in this latent stage for a lifetime without causing disease or, under certain conditions, it can awake resulting in TB disease. In this context, the aim of our study is to identify and characterize non-coding RNAs (ncRNAs) transcribed under genotoxic stress as well as during reactivation from the dormant stage. Here, Mtb strain H37Rv was exposed to various forms of genotoxic stress (oxidative, nitrosative or alkylative stress or double strand DNA breaks) and defined culture supplements. Total RNA from treated and untreated H37Rv cells was isolated and subjected to high-throughput RNA-seq. ncRNAs were identified using Rockhopper. A subset of the ncRNAs detected was selected for a more detailed analysis, including validation by northern blot. The secondary structure of the ncRNAs under study was predicted using mfold and their potential gene targets were predicted using intaRNA and CopraRNA. Ahead, we will combine our molecular and bioinformatics results with in vitro studies, including mapping 5’ and 3’ by RACE, establishing their secondary structure with SHAPE, and detecting sRNA-mRNA interactions by performing EMSA. The potential physiological role of the Mtb ncRNAs predicted will be tested by employing mutants or by repression, deletion or over-expression of the ncRNA of interest and measuring the potential phenotypic outcome by next-generation quantitative mass spectrometry.

• Munoz, Marta Gomez (2016). Global transcriptional responses to genotoxic stress in Mycobacterium tuberculosis. Full text in Research Archive
• Munoz, Marta Gomez (2016). Transcriptional stress responses in Mycobacterium tuberculosis. Full text in Research Archive
• Munoz, Marta Gomez & Birhanu, Alemayehu Godana (2016). Exploring the transcriptomics and proteomics of Mycobacterium tuberculosis. Full text in Research Archive
• Munoz, Marta Gomez (2016). Research stay at the University of Cape Town (UCT), South Africa. Full text in Research Archive
• Munoz, Marta Gomez (2015). Global transcriptional responses to genotoxic stress in Mycobacterium tuberculosis. Full text in Research Archive

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