No abstract

Functionally uncharacterized UPF0118 family has been re-designated as autoinducer-2 exporter (AI-2E) family since one of its members, Escherichia coli YdgG, was identified to function as an AI-2E. However, it's very likely that AI-2E family members may exhibit significantly distinct functions due to low identities between them. Recently, we identified one member of this family designated as UPF0118 to represent a novel class of Na + (Li + )/H + antiporters. In this study, we presented that UPF0118, together with its homologs, should represent an independent group of AI-2E family, designated as Na + /H + Antiporter Group. Notably, this group shows five highly conserved motifs designated as Motifs A to E, which are not detected in the majority of AI-2E family members. Functional analysis established that polar or charged residues located in Motif A to D play a vital role in Na + (Li + )/H + antiport activity or pH response of UPF0118. However, three basic residues located in Motif E are not involved in the function of UPF0118, although the truncation of C terminus resulted in the non-expression of this transporter. Therefore, we propose that E 179 -R 182 -K 215 -Q 217 -D 251 -R 292 -R 293 -E 296 -K 298 -S 307 located in Motifs A to D can be used for signature functional motifs to recognize whether AI-2E family members function as Na + (Li + )/H + antiporters. Current findings positively contribute to the knowledge of molecular mechanism of Na + , Li + transporting and pH response of UPF0118, and the functional prediction of uncharacterized AI-2E family members.Keywords: UPF0118 family, Na + (Li + )/H + antiporter, functional motif, pH response, Na + (Li + ) translocation

In the cation diffusion facilitator (CDF) family, the transported substrates are confined to divalent metal ions, such as Zn 2+ , Fe 2+ , and Mn 2+ . However, this study identifies a novel CDF member designated MceT from the moderate halophile Planococcus dechangensis . MceT functions as a Na + (Li + , K + )/H + antiporter, together with its capability of facilitated Zn 2+ diffusion into cells, which have not been reported in any identified CDF transporters as yet. MceT is proposed to represent a novel CDF group, Na-CDF, which shares significantly distant phylogenetic relationship with three known CDF groups including Mn-CDF, Fe/Zn-CDF, and Zn-CDF. Variation of key function-related residues to “Y44-S48-Q150” in two structural motifs explains a significant discrimination in cation selectivity between Na-CDF group and three major known CDF groups. Functional analysis via site-directed mutagenesis confirms that MceT employs Q150, S158, and D184 for the function of MceT as a Na + (Li + , K + )/H + antiporter, and retains D41, D154, and D184 for its facilitated Zn 2+ diffusion into cells. These presented findings imply that MceT has evolved from its native CDF family function to a Na + /H + antiporter in an evolutionary strategy of the substitution of key conserved residues to “Q150-S158-D184” motif. More importantly, the discovery of MceT contributes to a typical transporter model of CDF family with the unique structural motifs, which will be utilized to explore the cation-selective mechanisms of secondary transporters.

Rational:Epithelioid hemangioendothelioma (EHE) is a rare neoplasm commonly known to arise from the soft tissue, lung, and liver. EHE arising from right innominate vein (RIV) has scarcely been reported in English literature.Patient concerns:Herein, we present a rare case of EHE of RIV in a 51-year-old woman with right-lower chest pain for 4 days. Computed tomography of the chest revealed a spherical mass with calcification and fatty foci located in the anterior mediastinum, thus a presumptive diagnosis of teratoma was made.Diagnoses, interventions, and outcomes:Video-assisted thoracoscopic explorations and resection of mediastinal tumor were then performed. The pathological examination showed that the tumor was EHE. Postoperative radiotherapy was delivered to the patient. Pulmonary metastases were found by chest CT a year after surgery.Lessons:A diagnosis of EHE might be considered, when a mediastinal tumor closely related to veins showing intratumoral calcification and obvious enhancement, despite the presence of a clear boundary and visible fat content.

DTI may be a more sensitive and accurate method to evaluate RIPNI compared with T2 measurements. FA and λ⊥ are promising quantitative indices in monitoring RIPNI. J. Magn. Reson. Imaging 2016;43:1492-1499.