Conservation of Complex Nuclear Localization Signals Utilizing Classical and Non-Classical Nuclear Import Pathways in LANA Homologs of KSHV and RFHV

ORF73 latency-associated nuclear antigen (LANA) of the Kaposi's sarcoma-associated herpesvirus (KSHV) is targeted to the nucleus of infected cells where it binds to chromatin and mediates viral episome persistence, interacts with cellular proteins and plays a role in latency and tumorigenesis. A structurally related LANA homolog has been identified in the retroperitoneal fibromatosis herpesvirus (RFHV), the macaque homolog of KSHV. Here, we report the evolutionary and functional conservation of a novel bi-functional nuclear localization signal (NLS) in KSHV and RFHV LANA. N-terminal peptides from both proteins were fused to EGFP or double EGFP fusions to examine their ability to induce nuclear transport of a heterologous protein. In addition, GST-pull down experiments were used to analyze the ability of LANA peptides to interact with members of the karyopherin family of nuclear transport receptors. Our studies revealed that both LANA proteins contain an N-terminal arginine/glycine (RG)-rich domain spanning a conserved chromatin-binding motif, which binds directly to importin β1 in a RanGTP-sensitive manner and serves as an NLS in the importin β1-mediated non-classical nuclear import pathway. Embedded within this domain is a conserved lysine/arginine-(KR)-rich bipartite motif that binds directly to multiple members of the importin α family of nuclear import adaptors in a RanGTP-insensitive manner and serves as an NLS in the classical importin α/β-mediated nuclear import pathway. The positioning of a classical bipartite kr-NLS embedded within a non-classical rg-NLS is a unique arrangement in these viral proteins, whose nuclear localization is critical to their functionality and to the virus life cycle. The ability to interact with multiple import receptors provides alternate pathways for nuclear localization of LANA. Since different import receptors can import cargo to distinct subnuclear compartments, a multifunctional NLS may provide LANA with an increased ability to interact with different nuclear components in its multifunctional role to maintain viral latency

AN EXPERIMENTAL STUDY OF STATIC AND DYNAMIC CHARACTERISTICS OF A 580MM (22.8IN.) DIAMETER DIRECT LUBRICATION TILTING PAD JOURNAL BEARING

ABSTRACT Direct lubrication tilting pad journal bearings (DLTPJ bearings) have rarely been applied to large scale rotating machinery, such as turbines or generators whose journal diameters are more than 500mm. In this paper, static and dynamic characteristics of a 580mm (22.8in.) diameter DLTPJ bearing were studied experimentally using a full scale bearing test rig. In the static test, distribution of metal temperature, oil film pressure and bearing loss were measured in changing oil flow rate, with mean bearing pressure ranging up to 2.9MPa. Maximum metal temperature of DLTPJ bearing was compared to that of conventional flood lubrication bearing, and it was confirmed that the direct lubrication can increase load capacity. In the dynamic test, spring and damping coefficients of oil film were obtained by exciting the bearing casing that was floated by air bellows. These data will be used for analysis and design of steam turbine rotors and their bearing systems. Also, vibration of pads was investigated, because metal failure on upper pads due to vibration has been found in some actual machines. In order to generate oil film pressure on the surface of upper pads, Rayleigh-step was machined there. And it was confirmed that vibration was reduced by Rayleigh-step

A light-independent oscillatory gene mPer3 in mouse SCN and OVLT.

A new member of the mammalian period gene family, mPer3, was isolated and its expression pattern characterized in the mouse brain. Like mPer1, mPer2 and Drosophila period, mPer3 has a dimerization PAS domain and a cytoplasmic localization domain. mPer3 transcripts showed a clear circadian rhythm in the suprachiasmatic nucleus (SCN). Expression of mPer3 was not induced by exposure to light at any phase of the clock, distinguishing this gene from mPer1 and mPer2. Cycling expression of mPer3 was also found outside the SCN in the organum vasculosum lamina terminalis (OVLT), a potentially key region regulating rhythmic gonadotropin production and pyrogen-induced febrile phenomena. Thus, mPer3 may contribute to pacemaker functions both inside and outside the SCN

Quantitative Analyses of Cryptochrome-mBMAL1 Interactions: MECHANISTIC INSIGHTS INTO THE TRANSCRIPTIONAL REGULATION OF THE MAMMALIAN CIRCADIAN CLOCK*

The mammalian cryptochromes mCRY1 and mCRY2 act as transcriptional repressors within the 24-h transcription-translational feedback loop of the circadian clock. The C-terminal tail and a preceding predicted coiled coil (CC) of the mCRYs as well as the C-terminal region of the transcription factor mBMAL1 are involved in transcriptional feedback repression. Here we show by fluorescence polarization and isothermal titration calorimetry that purified mCRY1/2CCtail proteins form stable heterodimeric complexes with two C-terminal mBMAL1 fragments. The longer mBMAL1 fragment (BMAL490) includes Lys-537, which is rhythmically acetylated by mCLOCK in vivo. mCRY1 (but not mCRY2) has a lower affinity to BMAL490 than to the shorter mBMAL1 fragment (BMAL577) and a K537Q mutant version of BMAL490. Using peptide scan analysis we identify two mBMAL1 binding epitopes within the coiled coil and tail regions of mCRY1/2 and document the importance of positively charged mCRY1 residues for mBMAL1 binding. A synthetic mCRY coiled coil peptide binds equally well to the short and to the long (wild-type and K537Q mutant) mBMAL1 fragments. In contrast, a peptide including the mCRY1 tail epitope shows a lower affinity to BMAL490 compared with BMAL577 and BMAL490(K537Q). We propose that Lys-537mBMAL1 acetylation enhances mCRY1 binding by affecting electrostatic interactions predominantly with the mCRY1 tail. Our data reveal different molecular interactions of the mCRY1/2 tails with mBMAL1, which may contribute to the non-redundant clock functions of mCRY1 and mCRY2. Moreover, our study suggests the design of peptidic inhibitors targeting the interaction of the mCRY1 tail with mBMAL1