Biology subjects

Lama, P.

Publications and source records attributed to Lama, P..

4 recordsLinked to original sources

bioRxiv2022

Peptide derived nanobody inhibits entry of SARS-CoV-2 variants

Emergence of the new escape mutants of the SARS-CoV-2 virus has escalated its penetration among the human population and has reinstated its status as a global pandemic. Therefore, developing effective antiviral therapy against emerging SARS variants and other viruses in a short period of time becomes essential. Blocking the SARS-CoV-2 entry into human host cells by disrupting the spike glycoprotein-ACE2 interaction has been already exploited for vaccine development and monoclonal antibody therapy. Unlike the previous reports, our study used a 9 amino acid peptide from the receptor-binding motif (RBM) of Spike (S) protein as an epitope. We report the identification of an efficacious nanobody N1.2 that blocks the entry of pseudovirus containing SARS-CoV-2 spike as the surface glycoprotein. Moreover, we observe a more potent neutralizing effect against both the hCoV19 (Wuhan/WIV04/2019) and the Omicron (BA.1) pseudotyped spike virus with a bivalent version of the nanobody. In summary, our study presents a faster and efficient methodology to use peptide sequences from a protein-receptor interaction interface as epitopes for screening nanobodies against potential pathogenic targets. This approach can also be widely extended to target other viruses and pathogens in the future.

cell biology↗

bioRxiv2021

Initiation of ensemble kinesin-3 motility is regulated by the rigidity of cargo-motor attachment

Intracellular cargo transport is powered by molecular motors that move on their respective filamentous tracks. A key component in this process is the tether between cargo and motor, which is often connected by long slender coiled-coils. Several studies have identified mechanisms that regulate cargo transport and can be broadly categorized into regulation of the motor ATPase activity by autoinhibition, cargo adapters and modifications in the cytoskeletal tracks. The regulatory effects of cargo-motor linkers have been described in kinesin-3 subfamily motors. However, the effects of cargo-motor linker rigidity on ensemble cargo transport has not been explored. Here we have built a DNA origami scaffold, which can be tethered with multiple kinesin-3 motors using either single or double-stranded DNA linkages, mimicking rigid versus flexible cargo-motor linkages. Using this system, we show that regardless of the motor numbers attached to the cargo, only linkers with a lesser degree of freedom allow motors to engage with microtubule tracks. Together, our work identifies that the rigidity of cargo-motor linkages influences motor motility. This opens up the possibilities to identify new factors that can influence the rigidity of cargo-motor linkages that in turn can regulate intracellular cargo transport.

biochemistry↗

bioRxiv2020

Genetically encoded live cell sensor for tyrosinated microtubules

Microtubule cytoskeleton exists in various biochemical forms in different cells due to tubulin post-translational modification (PTMs). These PTMs are known to affect microtubule stability, dynamics and interaction with MAPs and motors in a specific manner, widely known as tubulin code hypothesis. At present there exist no tool that can specifically mark tubulin PTMs in live cells, thus severely limiting our understanding of tubulin PTMs. Using yeast display library, we identified a binder against terminal tyrosine of alpha tubulin, a unique PTM site. Extensive characterization validates the robustness and non-perturbing nature of our binder as tyrosination sensor, a live cell tubulin nanobody specific towards tyrosinated or unmodified microtubules. Using which, in real time we followed nocodazole, colchicine and vincristine induced depolymerization events of unmodified microtubules, and found each distinctly perturb microtubule polymer. Together, our work describes the tyrosination sensor and potential applications to study microtubule and PTM processes in living cells.

cell biology↗

bioRxiv2017

FEMALE CHEMICAL WARFARE DRIVES FITNESS EFFECTS OF GROUP SEX RATIO

In animals, skewed sex ratios can affect individual fitness either via sexual interactions (e.g. intersexual conflict or intrasexual mate competition) or non-sexual interactions (e.g. sex-specific resource competition). Because most analyses of sex ratio focus on sexual interactions, the relative importance of these mechanisms remains unclear. We addressed this problem using the flour beetle Tribolium castaneum, where male-biased sex ratios increase female fitness relative to unbiased or female-biased groups. Although flour beetles show both sexual and non-sexual (resource) competition, we found that sexual interactions did not explain female fitness. Instead, female fecundity was dramatically reduced even after a brief exposure to flour conditioned by other females. Earlier studies suggested that quinones (secreted toxins) might mediate density-dependent population growth in flour beetles. We identified ethyl- and methyl-benzoquinone (EBQ and MBQ) as the primary components of adult stink glands that regulate female fecundity. In female-biased groups (i.e. at high female density), females upregulated quinones and suppressed each others reproduction. In male-biased groups, low female density lead to low quinone levels, allowing higher fecundity. Thus, quinones serve both as indicators and mediators of female competition, resulting in the observed fitness decline in female-biased groups. Our results underscore the importance of non-sexual interference competition that may often underlie the fitness consequences of skewed sex ratios.

evolutionary biology↗