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Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is widely used to treat malignant hematological neoplasms and non-malignant hematological disorders. Approximately, 5000 allo-HSCT procedures are performed in China annually. Substantial progress has been made in haploidentical HSCT (HID-HSCT), pre-transplantation risk stratification, and donor selection in allo-HSCT, especially after the establishment of the “Beijing Protocol” HID-HSCT system. Transplant indications for selected subgroups in low-risk leukemia or severe aplastic anemia (SAA) differ from those in the Western world. These unique systems developed by Chinese doctors may inspire the refining of global clinical practice. We reviewed the efficacy of allo-HSCT practice from available Chinese studies on behalf of the HSCT workgroup of the Chinese Society of Hematology, Chinese Medical Association and compared these studies to the consensus or guideline outside China. We summarized the consensus on routine practices of all-HSCT in China and focused on the recommendations of indications, conditioning regimen, and donor selection.

Driven by the energy of ATP binding and hydrolysis, ATP binding cassette (ABC) transporters alternate between inward-and outward-facing conformations allowing vectorial movement of substrates. Conflicting models have been proposed to describe the conformational motion underlying this switch in access of the transport pathway. One model, based on three crystal structures of the lipid flippase MsbA, envisions a large amplitude motion that disengages the nucleotide binding domains and repacks the transmembrane helices. To test this model and place the crystal structures in a mechanistic context, we use spin labeling and Double Electron Electron Resonance (DEER) spectroscopy to define the nature and amplitude of MsbA conformational change during ATP hydrolysis cycle. For this purpose, spin labels were introduced at sites selected to provide a distinctive pattern of distance changes unique to the crystallographic transformation. Distance changes in liposomes, induced by the transition from nucleotide-free MsbA to the highest energy intermediate, fit a simple pattern whereby residues on the cytoplasmic side undergo 20-30Å closing motion while a 7-10Å opening motion is observed on the extracellular side. The transmembrane helices undergo relative movement to create the outward opening consistent with that implied by the crystal structures. DEER distance distributions reveal asymmetric backbone flexibility on the two sides of the transporter that correlates with asymmetric opening of the substrate binding chamber. Together with extensive accessibility analysis, our results suggest that these structures capture features of the motion that couples ATP energy expenditure to work providing a framework for the mechanism of substrate transport. KeywordsABC transporter; MsbA; double electron-electron resonance (DEER); site-directed spin labeling; electron paramagnetic resonance Active transporters transduce various forms of energy into the mechanical work of substrate translocation. For the class of ATP binding cassettes (ABC) transporters, ATP energy drives protein conformational motions to carry molecules ranging from small ions to large polypeptides across membranes 1,2 . The spectrum of these movements, their amplitudes and *Corresponding author. Mailing address for Hassane S. Mchaourab: 741 Light Hall, 2215 Garland Ave., Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN 37232, USA, hassane.mchaourab@vanderbilt.edu. ⊥ Current address: Dept. Scienze Chimiche, Universita' degli studi di Padova, Padova, Italy.Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers tha...

We measured the amplitude of conformational motion in the ATP-binding cassette (ABC) transporter MsbA upon lipopolysaccharide (LPS) binding and following ATP turnover by pulse double electron-electron resonance and fluorescence homotransfer. The distance constraints from both methods reveal large-scale movement of opposite signs in the periplasmic and cytoplasmic part of the transporter upon ATP hydrolysis. LPS induces distinct structural changes that are inhibited by trapping of the transporter in an ATP post-hydrolysis intermediate. The formation of this intermediate involves a 33-Å distance change between the two ABCs, which is consistent with a dimerization-dissociation cycle during transport that leads to their substantial separation in the absence of nucleotides. Our results suggest that ATP-powered transport entails LPS sequestering into the open cytoplasmic chamber prior to its translocation by alternating access of the chamber, made possible by 10–20-Å conformational changes.

Human herpesvirus 6 (HHV-6), which belongs to the betaherpesvirus subfamily and infects mainly T cells in vitro, causes acute and latent infections. Two variants of HHV-6 have been distinguished on the basis of differences in several properties. We have determined the complete DNA sequence of HHV-6 variant B (HHV-6B) strain HST, the causative agent of exanthem subitum, and compared the sequence with that of variant A strain U1102. A total of 115 potential open reading frames (ORFs) were identified within the 161,573-bp contiguous sequence of the entire HHV-6 genome, including some genes with remarkable differences in amino acid identity. All genes with <70% identity between the two variants were found to contain deleted regions when ORFs that could not be expressed were excluded from the comparison. Except in the case of U47, these differences were found in immediate-early/regulatory genes, DR2, DR7, U86/90, U89/90, and U95, which may represent characteristic differences of variants A and B. Also, we have successfully typed 14 different strains belonging to variant A or B by PCR using variant-specific primers; the results suggest that the remarkable differences observed were conserved evolutionarily as variant-specific divergence.