Structural basis of sodium-dependent bile salt uptake into the liver.

The liver takes up bile salts from blood to generate bile, enabling absorption of lipophilic nutrients and excretion of metabolites and drugs. Human Na-taurocholate co-transporting polypeptide (NTCP) is the main bile salt uptake system in liver. NTCP is also the cellular entry receptor of human hepatitis B and D viruses (HBV/HDV), and has emerged as an important target for antiviral drugs.

The fused SnoaL_2 domain in the Mycobacterium tuberculosis sigma factor σJ modulates promoter recognition.

Extra-cytoplasmic function (ECF) σ-factors are widespread in bacteria, linking environmental stimuli with changes in gene expression. These transcription factors span several phylogenetically distinct groups and are remarkably diverse in their activation and regulatory mechanisms. Here, we describe the structural and biochemical features of a Mycobacterium tuberculosis ECF factor σJ that suggests that the SnoaL_2 domain at the C-terminus can modulate the activity of this initiation factor in the absence of a cognate regulatory anti-σ factor.

Crystallographic studies of the extracytoplasmic function σ factor σ(J) from Mycobacterium tuberculosis.

Mycobacterium tuberculosis has multiple σ factors which enable the bacterium to reprogram its transcriptional machinery under diverse environmental conditions. σ(J), an extracytoplasmic function σ factor, is upregulated in late stationary phase cultures and during human macrophage infection. σ(J) governs the cellular response to hydrogen peroxide-mediated oxidative stress.

Assessment of five soil DNA extraction methods and a rapid laboratory-developed method for quality soil DNA extraction for 16S rDNA-based amplification and library construction.

Extraction of DNA from soil samples using standard methods often results in low yield and poor quality making them unsuitable for community analysis through polymerase chain reaction (PCR) due to the formation of chimeric products with smaller template DNAs and the presence of humic substances. The present study focused on the assessment of five different methods for metagenomic DNA isolation from soil samples on the basis of processing time, purity, DNA yield, suitability for PCR, restriction digestion and mDNA library construction. A simple and rapid alkali lysis based on indirect DNA extraction from soil was developed which could remove 90% of humic substances without shearing the DNA and permits the rapid and efficient isolation of high quality DNA without the requirement of hexadecyltrimethylammonium bromide and phenol cleanup.

Inter-domain interactions influence the stability and catalytic activity of the bi-domain protein tyrosine phosphatase PTP99A.

The two protein tyrosine phosphatase (PTP) domains in bi-domain PTPs share high sequence and structural similarity. However, only one of the two PTP domains is catalytically active. Here we describe biochemical studies on the two tandem PTP domains of the bi-domain PTP, PTP99A.