The heparin-binding hemagglutinin protein of Mycobacterium tuberculosis is a nucleoid-associated protein.

Nucleoid-associated proteins (NAPs) regulate multiple cellular processes such as gene expression, virulence, and dormancy throughout bacterial species. NAPs help in the survival and adaptation of Mycobacterium tuberculosis (Mtb) within the host. Fourteen NAPs have been identified in Escherichia coli; however, only seven NAPs are documented in Mtb. Given its complex lifestyle, it is reasonable to assume that Mtb would encode for more NAPs. Using bioinformatics tools and biochemical experiments, we have identified the heparin-binding hemagglutinin (HbhA) protein of Mtb as a novel sequence-independent DNA-binding protein which has previously been characterized as an adhesion molecule required for extrapulmonary dissemination. Deleting the carboxy-terminal domain of HbhA resulted in a complete loss of its DNA-binding activity. Atomic force microscopy showed HbhA-mediated architectural modulations in the DNA, which may play a regulatory role in transcription and genome organization. Our results showed that HbhA colocalizes with the nucleoid region of Mtb. Transcriptomics analyses of a hbhA KO strain revealed that it regulates the expression of ∼36% of total and ∼29% of essential genes. Deletion of hbhA resulted in the upregulation of ∼73% of all differentially expressed genes, belonging to multiple pathways suggesting it to be a global repressor. The results show that HbhA is a nonessential NAP regulating gene expression globally and acting as a plausible transcriptional repressor.

Phylogenetic analysis and interactomics study unveil gene co-optive evolution of LysR-type transcription regulators across non-pathogenic, opportunistic, and pathogenic mycobacteria.

Mycobacterial species is known for inhabiting various niches ranging from soil to harsh intracellular environment of animal hosts and their survival through constant changes. For survival and persistence, these organisms must quickly adapt by bringing shift in their metabolism. Metabolic shifts are brought by sensing the environmental cues usually by membrane localized sensor molecules. These signals are transmitted to regulators of various metabolic pathways leading to post-translational modifications of regulators ultimately resulting in altered metabolic state of the cell. Multiple regulatory mechanisms have been unearthed so far that play crucial role in adapting to these situations, and among them, the signal-dependent transcriptional regulators mediated responses are integral for the microbes to perceive environmental signals and generate appropriate adaptive responses. LysR-type transcriptional regulators (LTTRs) form the largest family of transcriptional regulators, which are present in all kingdoms of life. Their numbers vary among bacterial genera and even in different mycobacterial species. To understand the evolutionary aspect of pathogenicity based on LTTRs, we performed phylogenetic analysis of LTTRs encoded by several mycobacterial species representing non-pathogenic (NP), opportunistic (OP), and totally pathogenic (TP) mycobacteria. Our results showed that LTTRs of TP clustered separately from LTTRs of NP and OP mycobacteria. In addition, LTTRs frequency per Mb of genome was reduced in TP when compared with NP and OP. Further, the protein-protein interactions and degree-based network analysis showed concomitant increased interactions per LTTRs with increase in pathogenicity. These results suggested the increase in regulon of LTTRs during evolution of TP mycobacteria.

ClpC-Mediated Sporulation Regulation at Engulfment Stage in Bacillus anthracis.

Bacterial sporulation is a conserved process utilized by members of Bacillus genus and Clostridium in response to stress such as nutrient or temperature. Sporulation initiation is triggered by stress signals perceived by bacterial cell that leads to shutdown of metabolic pathways of bacterial cells. The mechanism of sporulation involves a complex network that is regulated at various checkpoints to form the viable bacterial spore. Engulfment is one such check point that drives the required cellular rearrangement necessary for the spore assembly and is mediated by bacterial proteolytic machinery that involves association of various Clp ATPases and ClpP protease. The present study highlights the importance of degradation of an anti-sigma factor F, SpoIIAB by ClpCP proteolytic machinery playing a crucial role in culmination of engulfment process during the sporulation in Bacillus anthracis.

Diagnostic Accuracy of Color Doppler and Calcium Scoring versus Dual-Energy Computed Tomography Angiography in the Assessment of Peripheral Arterial Diseases of Lower Limb.

OBJECTIVES: Peripheral arterial disease (PAD) leads to narrowing and hardening of arteries which leads to increased risk of lower extremity amputation. Hence, the accuracy of non-invasive diagnostic methods such as calcium scoring and color Doppler needs to be assessed in comparison to the gold standard dual-energy computed tomography (DECT) angiography. This study aims to evaluate the accuracy of color Doppler and calcium scoring when compared to DECT angiography in the assessment of PAD of the lower limb. It is a cross- sectional retrospective study. MATERIAL AND METHODS: The study included 55 patients aged between 40 and 70 years. All the patients with symptoms suggestive of PAD underwent color Doppler study of lower limb arterial system. Afterward, the patient underwent CT angiography. The first plain images were taken for calcium scoring following which contrast was given and further images were taken. RESULTS: As compared to CT angiography assessment, Doppler assessment was 88.1% sensitive but only 69.2% specific with diagnostic accuracy of 83.6%. For angiographically detected atheromatous changes, color Doppler had sensitivity and specificity of 86.2% and 76.9%. The derived cutoff value >149.1 of calcium score in lower limb arteries was in 100% agreement with CT angiography detected PAD, whereas, for atheromatous changes, total calcium score at a cutoff value of >842.2 had sensitivity and specificity of 75.9% and 80.8%. CONCLUSION: Calcium scoring as compared to color Doppler has a higher diagnostic efficacy for the detection of DECT angiography confirmed PAD, whereas calcium score lacks adequate sensitivity at projected cutoff in the evaluation of atheromatous changes.

Crossed Fused Renal Ectopia with Single Ureter and Single Renal Vein: A Rare Case.

Crossed fused renal ectopia with a single ureter and single renal vein is a rare congenital anomaly in which both the fused kidneys lie on one side of the body. We present an unusual case of crossed fused renal ectopia with a single ureter, single renal vein, and a calculus in a 22-year-old man who presented with lower abdominal pain, burning micturition, and a right-side abdominal lump present for three months. On abdominal ultrasound and non-contrast computed tomography (CT), the left kidney was not visualized in the left renal fossa. However, we noted it on the right side, fused to the lower pole of the right kidney with a calculus within the pelvis leading to mild hydronephrosis. After intravenous administration of non-ionic contrast medium, we saw a single ureter draining both the moieties into the urinary bladder on the right side. A three-dimensional volume rendering technique revealed a single renal vein draining the renal parenchyma into the inferior vena cava. Cross fused renal ectopia is an uncommon congenital anomaly which remains asymptomatic throughout life and undetected in the absence of renal pathologies. Multi-detector computed tomography (MDCT) is an excellent tool for denoting anatomical details of this anomaly; the information provided by MDCT is crucial for surgeons, nephrologists, and radiologists alike in facilitating proper management of the condition.