1. Ubiquicidin-Derived Peptides Selectively Interact with the Anionic Phospholipid Membrane
Jyotsna Bhatt Mitra, Veerendra K Sharma, Archana Mukherjee, V Garcia Sakai, Ashutosh Dash, Mukesh Kumar Langmuir. 2020 Jan 14;36(1):397-408. doi: 10.1021/acs.langmuir.9b03243. Epub 2019 Dec 26.
Ubiquicidin (UBI)/ribosomal protein S30 (RS30) is an intracellular protein with antimicrobial activities against various pathogens. UBI (29-41) and UBI (31-38) are two crucial peptides derived from Ubiquicidin, which have shown potential as infection imaging probes. Here, we report the interactions of UBI-derived peptides with anionic and zwitterionic phospholipid membranes. Our isothermal titration calorimetry results show that both peptides selectively interact with the anionic phospholipid membrane (a model bacterial membrane) and reside mainly on the membrane surface. The interaction of UBI-derived peptides with the anionic phospholipid membrane is exothermic and driven by both enthalpy (ΔH) and entropy (ΔS), with the entropic term TΔS being greater than ΔH. This large entropic term can be a result of the aggregation of the anionic vesicles, which is confirmed by dynamic light scattering (DLS) measurements. DLS data show that vesicle aggregation is enhanced with increasing peptide-to-lipid molar ratios (P/L) and is found to be more pronounced in the case of UBI (29-41). DLS results are found to be consistent with independent transmission measurements. To study the effects of UBI-derived peptides on the microscopic dynamics of the model bacterial membrane, quasielastic neutron scattering (QENS) measurements have been carried out. The QENS results show that both peptides restrict the lateral motion of the lipid within the leaflet. UBI (29-41) acts as a stronger stiffening agent, hindering the lateral diffusion of lipids more efficiently than UBI (31-38). To our knowledge, this is the first report illustrating the mechanism of interaction of UBI-derived peptides with model membranes. This study also has implications for the improvement and design of antimicrobial peptide-based infection imaging probes.
2. Infected Lower Limb Megaprosthesis on 68Ga-NOTA-Ubiquicidin PET/CT Imaging
Prateek Kaushik, Satya Dev Maurya, Nishikant Damle, Sanjana Ballal, Venkatesan Sampath Kumar, Chandrasekhar Bal, Madhavi Tripathi Nucl Med Mol Imaging. 2022 Jun;56(3):171-172. doi: 10.1007/s13139-022-00747-5. Epub 2022 Apr 11.
Pain after prosthesis implant is a common clinical problem which requires distinction of septic from aseptic causes since the treatment differs. Non-invasive imaging methods play an important role in the diagnosis. Radiolabelled ubiquicidin can be used for imaging infection by binding directly to bacterial cell wall. We describe a case of a 24-year-old man with right lower limb megaprosthesis which did not show any loosening on computed tomography (CT) but was accurately diagnosed as infected prosthesis with 68Ga-NOTA-ubiquicidin(29-41) acetate scan.