Dynamic action of an intrinsically disordered protein in DNA compaction that induces mycobacterial dormancy.

Mycobacteria are the major human pathogens with the capacity to become dormant persisters. Mycobacterial DNA-binding protein 1 (MDP1), an abundant histone-like protein in dormant mycobacteria, induces dormancy phenotypes, e.g. chromosome compaction and growth suppression. For these functions, the polycationic intrinsically disordered region (IDR) is essential. However, the disordered property of IDR stands in the way of clarifying the molecular mechanism. Here we clarified the molecular and structural mechanism of DNA compaction by MDP1. Using high-speed atomic force microscopy, we observed that monomeric MDP1 bundles two adjacent DNA duplexes side-by-side via IDR. Combined with coarse-grained molecular dynamics simulation, we revealed the novel dynamic DNA cross-linking model of MDP1 in which a stretched IDR cross-links two DNA duplexes like double-sided tape. IDR is able to hijack HU function, resulting in the induction of strong mycobacterial growth arrest. This IDR-mediated reversible DNA cross-linking is a reasonable model for MDP1 suppression of the genomic function in the resuscitable non-replicating dormant mycobacteria.

Lenvatinib plus pembrolizumab versus sunitinib for advanced renal cell carcinoma: Japanese patients from the CLEAR study.

BACKGROUND: The phase 3 CLEAR study demonstrated statistically significantly improved efficacy with lenvatinib plus pembrolizumab versus sunitinib, including progression-free survival and overall survival, in patients with previously untreated advanced renal cell carcinoma. This subset analysis investigated efficacy and safety in Japanese patients randomized to lenvatinib plus pembrolizumab or sunitinib in the CLEAR study. METHODS: Progression-free survival, overall survival, tumor response, and safety were assessed in Japanese patients with previously untreated advanced renal cell carcinoma randomized to receive lenvatinib plus pembrolizumab (n = 42) or sunitinib (n = 31). Efficacy outcomes were analyzed by independent imaging review per Response Evaluation Criteria in Solid Tumors, version 1.1. RESULTS: Progression-free survival was longer with lenvatinib plus pembrolizumab than with sunitinib (median, 22.1 vs. 10.9 months; hazard ratio, 0.39; 95% CI, 0.20-0.74). Median overall survival was not estimable in the lenvatinib plus pembrolizumab arm and 30.6 months in the sunitinib arm (HR, 1.20; 95% CI, 0.39-3.66). Overall survival adjusted for the imbalance of Memorial Sloan-Kettering Cancer Center prognostic risk group favored lenvatinib plus pembrolizumab (hazard ratio, 0.67; 95% CI, 0.18-2.39). Objective response rate (69.0% vs. 45.2%; odds ratio, 2.71; 95% CI, 1.03-7.10) was higher and median duration of response (20.3 vs. 9.1 months) was longer with lenvatinib plus pembrolizumab versus sunitinib. Grade ≥ 3 treatment-emergent adverse events occurred in 95.2% versus 87.1% of patients in the lenvatinib plus pembrolizumab versus sunitinib arms. CONCLUSIONS: These findings support lenvatinib plus pembrolizumab as a potential first-line treatment for Japanese patients with advanced renal cell carcinoma.

Structure-dependent electronic nature of star-shaped oligothiophenes, probed by ensemble and single-molecule spectroscopy.

We have investigated the photophysical properties of star-shaped oligothiophenes with three terthiophene arms (meta to each other, S3) or six terthiophene arms (ortho-, meta-, and para-arranged, S6) connected to an ethynylbenzene core to elucidate the relationship between their molecular structure and electronic properties by using a combination of ensemble and single-molecule spectroscopic techniques. We postulate two different conformations for molecules S3 and S6 on the basis of the X-ray structure of hexakis(5-hexyl-2-thienlyethynyl)benzene and suggest the coexistence of these conformers by using spectroscopic methods. From the steady-state spectroscopic data of compound S6, we show that the exciton is delocalized over the core structure, but that the meta-linkage in compound S3 prevents the electronic communication between the arms. However, in single-molecule spectroscopic measurements, we observed that some molecules of compound S3 showed long fluorescence lifetimes (about 1.4 ns) in the fluorescence-intensity trajectories, which indicated that π electrons were delocalized along the meta linker. Based on these observations, we suggest that the delocalized exciton is intensely sensitive towards the dihedral angle between the core and the adjacent thiophene ring, as well as to the substituted position of the terthiophene arms. Our results highlight that the fluorescence lifetimes of compounds S3 and S6 are strongly correlated with the spatial location of their excitons, which is mainly affected by their conformation, that is, whether the innermost thiophene rings are facing each other or not. More interestingly, we observed that the difference between the degrees of ring-torsional flexibility of compounds S3 and S6 results in their sharply contrasting fluorescence properties, such as a change in fluorescence intensity as a function of temperature.

Pyrrole-fused azacoronene family: the influence of replacement with dialkoxybenzenes on the optical and electronic properties in neutral and oxidized states.

A novel pyrrole-fused azacoronene family was synthesized via oxidative cyclodehydrogenation of the corresponding hexaarylbenzenes as the key step, and the crystal structures of tetraazacoronene 3b and triazacoronene 4a were elucidated. The photophysical properties for neutral compounds 1-4 were investigated using steady-state UV-vis absorption/emission spectroscopy and time-resolved spectroscopy (emission spectra and lifetime measurements) at both room temperature and 77 K. The observation of both fluorescence and phosphorescence allowed us to estimate the small S1-T1 energy gap (ΔES-T) to be 0.35 eV (1a), 0.26 eV (2a), and 0.36 eV (4a). Similar to the case of previously reported hexapyrrolohexaazacoronene 1 (HPHAC), electrochemical oxidation revealed up to four reversible oxidation processes for all of the new compounds. The charge and spin delocalization properties of the series of azacoronene π-systems were examined using UV-vis-NIR absorption, ESR, and NMR spectroscopies for the chemically generated radical cations and dications. Combined with the theoretical calculations, the experimental results clearly demonstrated that the replacement of pyrrole rings with dialkoxybenzene plays a critical role in the electronic communication, where resonance structures significantly contribute to the thermodynamic stability of the cationic charges/spins and determine the spin multiplicities. For HPHAC 1 and pentaazacoronene 2, the overall aromaticity predicted for closed-shell dications 1(2+) and 2(2+) was primarily based on the theoretical calculations, and the open-shell singlet biradical or triplet character was anticipated for tetraazacoronene 3(2+) and triazacoronene 4(2+) with the aid of theoretical calculations. These polycyclic aromatic hydrocarbons (PAHs) represent the first series of nitrogen-containing PAHs that can be multiply oxidized.