No abstract

The cellular nucleolar proteins are reported to facilitate the replication cycles of some human and animal viruses by interaction with viral proteins. In this study, a nucleolar phosphoprotein B23 was identified to interact with Newcastle disease virus (NDV) matrix (M) protein. We found that NDV M protein accumulated in the nucleolus by binding B23 early in infection, but resulted in the redistribution of B23 from the nucleoli to the nucleoplasm later in infection. In vitro binding studies utilizing deletion mutants indicated that amino acids 30-60 of M and amino acids 188-245 of B23 were required for binding. Furthermore, knockdown of B23 by siRNA or overexpression of B23 or M-binding B23-derived polypeptides remarkably reduced cytopathic effect and inhibited NDV replication. Collectively, we show that B23 facilitates NDV replication by targeting M to the nucleolus, demonstrating for the first time a direct role for nucleolar protein B23 in a paramyxovirus replication process.

The emerging H5 clade 2.3.4.6 viruses of different NA subtypes have been detected in different domestic poultry in China. We evaluated the receptor binding property and transmissibility of four novel H5 clade 2.3.4.6 subtype highly pathogenic avian influenza viruses. The results show that these viruses bound to both avian-type (α-2,3) and human-type (α-2,6) receptors. Furthermore, we found that one of these viruses, GS/EC/1112/11, not only replicated but also transmitted efficiently in guinea pigs. Therefore, such novel H5 subtype viruses have the potential of a pandemic threat.

CYS3 is the positive-acting global regulatory protein involved in the sulfur control circuit in Neurospora crassa and belongs to the family of bZIP DNA-binding proteins. Here we report a characterization of native DNA-binding sites recognized by CYS3. DNA footprinting experiments and systematic mutational analysis were used to define the consensus CYS3-binding sequence, 5'-ATGPuPyPuPyCAT, a 10-bp palindrome. The sequence 5'-ATGACGTCAT acts as a strong binding site, and all single nucleotide changes within this sequence resulted in a reduction, or even complete loss, of CYS3 DNA-binding. Site-directed mutagenesis was employed to study two uncharged residues, serine 113 and phenylalanine 116, in the basic region of the CYS3 protein bZip DNA-binding domain. Ser113 appears to be directly involved in a specific interaction with nucleotide 2 of the binding site, possibly by making a direct contact with this base, and Phe116 contributes significantly to DNA-binding affinity.

No abstract

No abstract

No abstract

No abstract