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Inosine triphosphatase (ITPA) is a ubiquitous key regulator of cellular non-canonical nucleotide levels. It breaks down inosine and xanthine nucleotides generated by deamination of purine bases. Its enzymatic action prevents accumulation of ITP and reduces the risk of incorporation of potentially mutagenic inosine nucleotides into nucleic acids. Here we describe the crystal structure of human ITPA

10-Formyltetrahydrofolate dehydrogenase is a ubiquitously expressed enzyme in the human body. It catalyses the formation of tetrahydrofolate and carbon dioxide from 10-formyltetrahydrofolate, thereby playing an important role in the human metabolism of one-carbon units. It is a two-domain protein in which the N-terminal domain hydrolyses 10-formyltetrahydrofolate into formate and tetrahydrofolate.

Efficient and rapid host cell invasion is a prerequisite for an intracellular parasitic life style. Pathogens typically induce receptor-mediated endocytosis and hijack the force-transducing system of a host cell to gain access to a replication-competent niche. In striking contrast, apicomplexan parasites such as Plasmodium, the causative agent of malaria, and the human and animal pathogens Toxopla

Cytidine triphosphate synthetase (CTPS) is a key enzyme in nucleic acid and phospholipid biosynthesis and its activity is increased in certain human cancers, making it a promising drug target. The crystal structure of the synthetase domain of human CTPS, which represents the first structure of a CTPS from an eukaryote, has been determined. The structure is homotetrameric and each active site is fo

Apicomplexan parasites such as Plasmodium and Toxoplasma display actomyosin-dependent motility in the absence of readily detectable actin polymers. Three recent studies indicate that parasite actin polymers, either harvested from parasites or formed from purified recombinant proteins, are exceptionally short ( approximately 100 nm). We propose that parasite motility could be directed by the transi

ADF/cofilins (AC) are essential F- and G-actin binding proteins that modulate microfilament turnover. The genome of Plasmodium falciparum, the parasite causing malaria, contains two members of the AC family. Interestingly, P. falciparum ADF1 lacks the F-actin binding residues of the AC consensus. Reverse genetics in the rodent malaria model system suggest that ADF1 performs vital functions during

Plasmodium falciparum, the etiologic agent of malaria, is a facultative intracellular parasite of the phylum Apicomplexa. A limited turnover of microfilaments takes place beneath the parasite plasma membrane, but the cytoplasm of apicomplexans is virtually devoid of F-actin. We produced Plasmodium actin in yeast. Purified recombinant Plasmodium actin polymerized inefficiently unless both gelsolin

In actin from many species H73 is methylated, but the function of this rare post-translational modification is unknown. Although not within bonding distance, it is located close to the gamma-phosphate of the actin-bound ATP. In most crystal structures of actin, the delta1-nitrogen of the methylated H73 forms a hydrogen bond with the carbonyl of G158. This hydrogen bond spans the gap separating sub

The SMC/Rad50/RecN proteins are universal DNA‐associated ABC‐type ATPases with crucial functions in genome maintenance. New insights into Rad50-DNA complex structure and cohesin regulation inspire a speculative look at the entire superfamily. Identification of a continuous DNA binding site across the Rad50 dimer interface (Liu et al, 2016; Seifert et al, 2016) suggests a similar site in cohesin. T

In mammals, IgA is the antibody class that is produced in largest quantities. The main producers are plasma cells located in the lamina propria at mucosal surfaces that secrete it as dimers covalently linked to the J chain. Polymeric immunoglobulin receptors (pIgRs) expressed on epithelial cells bind to dimeric IgA molecules and mediate basolateral to apical transcytosis, before IgA is released in

Pupillary contagion occurs when one's pupil size unconsciously adapts to the pupil size of an observed individual and is presumed to reflect the transfer of arousal. Importantly, when estimating pupil contagion, low level stimuli properties need to be controlled for, to ensure that observations of pupillary changes are due to internal change in arousal rather than the external differences between