Ion-Powered Rotary Motors: Where Did They Come from and Where They Are Going?

Molecular motors are found in many living organisms. One such molecular machine, the ion-powered rotary motor (IRM), requires the movement of ions across a membrane against a concentration gradient to drive rotational movement. The bacterial flagellar motor (BFM) is an example of an IRM which relies on ion movement through the stator proteins to generate the rotation of the flagella. There are many ions which can be used by the BFM stators to power motility and different ions can be used by a single bacterium expressing multiple stator variants. The use of ancestral sequence reconstruction (ASR) and functional analysis of reconstructed stators shows promise for understanding how these proteins evolved and when the divergence in ion use may have occurred. In this review, we discuss extant BFM stators and the ions that power them as well as recent examples of the use of ASR to study ion-channel selectivity and how this might be applied to further study of the BFM stator complex.

Evolutionary, genetic, structural characterization and its functional implications for the influenza A (H1N1) infection outbreak in India from 2009 to 2017.

Influenza A (H1N1) continues to be a major public health threat due to possible emergence of a more virulent H1N1 strain resulting from dynamic changes in virus adaptability consequent to functional mutations and antigenic drift in the hemagglutinin (HA) and neuraminidase (NA) surface proteins. In this study, we describe the genetic and evolutionary characteristics of H1N1 strains that circulated in India over a period of nine years from 2009 to 2017 in relation to global strains. The finding is important from a global perspective since previous phylogenetic studies have suggested that the tropics contributed substantially to the global circulation of influenza viruses. Bayesian phylogenic analysis of HA sequences along with global strains indicated that there is a temporal pattern of H1N1 evolution and clustering of Indian isolates with globally circulating strains. Interestingly, we observed four new amino acid substitutions (S179N, I233T, S181T and I312V) in the HA sequence of H1N1 strains isolated during 2017 and two (S181T and I312V) were found to be unique in Indian isolates. Structurally these two unique mutations could lead to altered glycan specificity of the HA gene. Similarly, sequence and structural analysis of NA domain revealed that the presence of K432E mutation in H1N1 strains isolated after 2015 from India and in global strains found to induce a major loop shift in the vicinity of the catalytic site. The findings presented here offer an insight as to how these acquired mutations could be associated to an improved adaptability of the virus for efficient human transmissibility.

Construction and conformational behavior of peptoids with cis-amide bond geometry: design of a peptoid with alternate φ, ψ values of inverse PP-II/PP-II and PP-I structures.

In peptoids due to the absence of amide protons, the backbone is devoid of hydrogen bond donor, linked by tertiary amide, which can be iso-energetic between cis and trans-amide bond geometry. The peptoids can be realized with cis amide bond if the side chain of ith residue can engage the carbonyl group of ith-1 residue in CH--O interactions. Simulations studies both in water and DMSO have been carried out. The peptoid Ac-(N(tle))(7) -NMe(2) can adopt degenerate conformations with alternate φ, ψ values of inverse PP-I and PP-I type structure's, or vice versa in water. In DMSO, Ac-(N(tle))(7)-NMe(2) also adopts inverse PP-I type structure. Like polyproline, molecule adopting a rigid structure can be used as molecular markers or spacers in biological studies.The peptoid Ac-(N(ala)-N(tle))(3)-NMe(2) with alternate trans and cis amide bond geometry for N(ala) and N(tle) residue corresponding to inverse PP-II/PP-II type and for N(tle) residue of PP-I type.