Plasmepsin V (PM V) is a pepsin-like aspartic protease essential for growth of the malaria parasite Plasmodium falciparum. Previous work has shown PM V to be an ER-resident protease that processes parasite proteins destined for export into the host cell. Depletion or inhibition of the enzyme is lethal during asexual replication within red blood cells, as well as during the formation of sexual stage gametocytes. The structure of the P. vivax PM V has been characterized by x-ray crystallography, revealing a canonical pepsin fold punctuated by structural features uncommon to secretory aspartic proteases. Here we use parasite genetics to probe these structural features by attempting to rescue lethal PM V depletion with various mutant enzymes. We find an unusual nepenthesin 1-type insert to be essential for parasite growth and PM V activity. Mutagenesis of the nepenthesin insert suggests that both its amino acid sequence and one of the two disulfide bonds that undergird its structure are required for the nepenthesin insert′s role in PM V function. Molecular dynamics simulations paired with Markov state modelling suggest that the nepenthesin insert allosterically controls PM V catalysis through multiple mechanisms.

A new species of green frog of the genus Euphlyctis Fitzinger, 1843 is described from West Bengal, a state of eastern India. A robust frog, SVL of male 86mm and that of female 132mm. The species is diagnosed by the presence of following characters: green dorsum and female with a greenish white mid-dorsal line, tibiotarsal articulation reaches eye, male with two vocal sac openings at the junction of jaw, female is larger than male though body parameters is proportionately longer in male, nostril snout length 3.45% of SVL, nostril much closer to snout tip than eye, units of hind limb i. e. thigh, shank and foot are almost equal in length, relative length of finger: II < IV < I < III. The new species is compared with existing eight species of the genus Euphlyctis.

A new species of the genus Microhyla, Microhyla bengalensis sp. nov., described from West Bengal state, India. The new species is distinguished from its congeners by a combination of the following morphological characters: 1) Small in size (SVL= 16.2 mm. in male); 2) truncated snout in dorsal view; 3) head wider than long (HW: HL= 1.36); 4) canthus rostralis and tympanum are indistinct; 5) nostril placed on the dorsal side of the snout; 6) tibiotarsal articulation not reaching the eye; 7) fingers and toes without disc; 8) toe webbing basal; 9) thigh and foot length are equal and smaller than shank; 10) skin tuberculated on dorsum; 11) 'teddy bear' dark brown mark on dorsum; 12) an inverted 'V'-shaped dark brown mark above the vent. A comparative morphological data of all the 14 Indian species of Microhyla is also provided.

Hydrogen exchange (HX) between protein amides and solvent water molecules can function as a probe for protein dynamics and provide a bridge between the experimental and computational worlds. However, it is important that the underlying assumptions are tested on well-known systems. Here we perform an analysis of a long MD simulation of BPTI, which has previously been used by Persson and Halle to propose a functional definition of the exchange-competent configurations. We find support for the hypothesis that the exchange-competent configurations typically do not constitute a metastable state per se, but rather occur as the outermost tail of the water distribution around a metastable broken state directly identifiable as having a broken intermolecular hydrogen bond and increased solvent-exposure. Furthermore, we estimate the lifetime of these broken states and the probability that exchange-competent configurations occur in them. We have also tested various sampling protocols and their ability to enhance the exploration of the broken states. Computational protocol used in this study can be applied to a broad range of sys-tems to gain valuable insight into the nature of the broken state, although further development is needed to devise a generally applicable quantitative method.