The Identification and Characterization of Sindbis Virus RNA:Host Protein Interactions

Arthropod-borne viruses, such as the members of genus Alphavirus, are a significant concern to global public health. As obligate intracellular pathogens, RNA viruses must interact with the host cell machinery to establish, and complete, their viral lifecycles. Despite considerable efforts to define the host/pathogen interactions essential for alphaviral replication, an unbiased and inclusive assessment of alphaviral RNA:protein interactions has not been undertaken. Moreover, the biological and molecular importance of these interactions, in the full context of their molecular function as RNA-binding proteins, has not been fully realized. The data presented here introduces a robust viral RNA:protein discovery method to elucidate the Sindbis virus (SINV) RNA:Protein host interface. Cross-Link Assisted mRNP Purification (CLAMP) assessment reveals an extensive array of host/pathogen interactions centered on the viral RNAs (vRNAs). After prioritization of the host proteins associated with the vRNAs, we identified the site of Protein:vRNA interaction via a CLIP-seq approach and assessed the consequences of the RNA:protein binding event of hnRNP K, hnRNP I, and hnRNP M in regards to viral infection. Herein we demonstrate that mutation of the prioritized hnRNP:vRNA interaction sites effectively disrupted the hnRNP:vRNA interaction. Correlating with disrupted hnRNP:vRNA binding, SINV growth kinetics were reduced relative to wild type parental viral infections in a vertebrate and invertebrate tissue culture models of infection. The molecular mechanism leading to reduced viral growth kinetics was found to be reduced vRNA accumulation and dysregulated structural gene expression. Collectively, this study further defines the scope and importance of the alphavirus host/pathogen vRNA:protein interactions. 5 CLIP-Seq samples in TOTAL- 2 Control Samples (Input and Empty), 3 immunoprecitations of hnRNP proteins (hnRNP K, I and M).