@article {65616, title = {Super-Resolution Fluorescence Imaging Reveals That Serine Incorporator Protein 5 Inhibits Human Immunodeficiency Virus Fusion by Disrupting Envelope Glycoprotein Clusters.}, journal = {ACS Nano}, year = {2020}, month = {2020 May 22}, abstract = {

Serine incorporator protein 5 (SERINC5) is the host anti-retroviral factor that reduces HIV-1 infectivity by incorporating into virions and inhibiting the envelope glycoprotein (Env) mediated virus fusion with target cells. We and others have shown that SERINC5 incorporation into virions alters the Env structure and sensitizes the virus to broadly neutralizing antibodies targeting cryptic Env epitopes. We have also found that SERINC5 accelerates the loss of Env function over time compared to control viruses. However, the exact mechanism by which SERINC5 inhibits HIV-1 fusion is not understood. Here, we utilized 2D and 3D super-resolution microscopy to examine the effect of SERINC5 on the distribution of Env glycoproteins on single HIV-1 particles. We find that, in agreement with a previous report, Env glycoproteins form clusters on the surface of mature virions. Importantly, incorporation of SERINC5, but not SERINC2, which lacks antiviral activity, disrupted Env clusters without affecting the overall Env content. We also show that SERINC5 and SERINC2 also form clusters on single virions. Unexpectedly, Env and SERINCs molecules exhibited poor co-distribution on virions, as evidenced by much greater Env-SERINC pairwise distances compare to Env-Env distances. This observation is inconsistent with the previously reported interaction between Env and SERINC5 and suggests an indirect effect of SERINC5 on Env cluster formation. Collectively, our results reveal a multifaceted mechanism of SERINC5-mediated restriction of HIV-1 fusion that, aside from the effects on individual Env trimers, involves disruption of Env clusters, which likely serve as sites of viral fusion with target cells.

}, issn = {1936-086X}, doi = {10.1021/acsnano.0c02699}, author = {Chen, Yen-Cheng and Sood, Chetan and Marin, Mariana and Aaron, Jesse and Gratton, Enrico and Salaita, Khalid and Melikyan, Gregory B} } @article {1439, title = {Like-charge interactions between colloidal particles are asymmetric with respect to sign.}, journal = {Soft Matter}, year = {2009}, month = {2009}, pages = {1931-6}, abstract = {

Two-dimensional dispersions of colloidal particles with a range of surface chemistries and electrostatic potentials are characterized under a series of solution ionic strengths. A combination of optical imaging techniques are employed to monitor both the colloid structure and the electrostatic surface potential of individual particles in situ. We find that like-charge multiparticle interactions can be tuned from exclusively repulsive to long-range attractive by changing the particle surface composition. This behavior is strongly asymmetric with respect to the sign of the surface potential. Collective long-range attractive interactions are only observed among negatively charged particles.

}, author = {Clack, Nathan G and Salaita, Khalid and Wu, HJ and Groves, JT and Gomez, EW} } @article {1437, title = {Electrostatic readout of DNA microarrays with charged microspheres.}, journal = {Nature Biotechnology}, volume = {26}, year = {2008}, month = {2008 Jul}, pages = {825-30}, abstract = {

DNA microarrays are used for gene-expression profiling, single-nucleotide polymorphism detection and disease diagnosis. A persistent challenge in this area is the lack of microarray screening technology suitable for integration into routine clinical care. Here, we describe a method for sensitive and label-free electrostatic readout of DNA or RNA hybridization on microarrays. The electrostatic properties of the microarray are measured from the position and motion of charged microspheres randomly dispersed over the surface. We demonstrate nondestructive electrostatic imaging with 10-mum lateral resolution over centimeter-length scales, which is four-orders of magnitude larger than that achievable with conventional scanning electrostatic force microscopy. Changes in surface charge density as a result of specific hybridization can be detected and quantified with 50-pM sensitivity, single base-pair mismatch selectivity and in the presence of complex background. Because the naked eye is sufficient to read out hybridization, this approach may facilitate broad application of multiplexed assays.

}, keywords = {Computer-Assisted, Gene Expression Profiling, Image Interpretation, Microspheres, Oligonucleotide Array Sequence Analysis, Static Electricity}, issn = {1546-1696}, doi = {10.1038/nbt1416}, author = {Clack, Nathan G and Salaita, Khalid and Groves, Jay T} }