The heterodimer NXF-1/NXT-1 is a conserved transport receptor essential for the export of messenger RNA (mRNA) from the nucleus to the cytoplasm for subsequent translation. The NXF-1/NXT-1 receptor facilitates this export through interactions with mRNA, the nucleoporins lining the nuclear pore complex (NPC), and interactions with components of two conserved multisubunit TRanscription-EXport complexes, TREX and TREX-2. These complexes play key roles in the biogenesis of mRNA, and their interactions with NXF-1/NXT-1 link mRNA transcription and processing to export. In Caenorhabditis elegans, TREX-2 may act as a tether between transcriptionally active gene promoters and the nuclear periphery to concentrate transcription and mRNA processing directly at the NPC (Rohner et al., 2013). This localization at the NPC is observed with the bidirectional heat-shock promoter
hsp-16.2/16.41 during heat-shock in C. elegans. In this study, we describe four new alleles found in a genetic screen for suppressors of a toxin expressed under
hsp-16.41 in C. elegans. We mapped three of these alleles to missense mutations within the functional domains of NXF-1 and one to the functional domain of NXT-1. These alleles confer no apparent phenotype under normal conditions but suppress the lethality of the toxin PEEL-1 when expressed under
hsp-16.41. However, when the PEEL-1 toxin is expressed endogenously, the
nxf-1(
yak65) allele does not suppress lethality, suggesting that suppression during heat-shock is unrelated to PEEL-1's native function. We propose that NXF-1/NXT-1 influences the expression of heat-shock activated genes due to an uncharacterized role in the recruitment of the heat-shock promoter to the NPC during heat-shock. This role may be mediated by interaction between NXF-1/NXT-1, nucleoporins, and TREX-2. The novel
nxf-1/nxt-1 alleles described in this study may disrupt these interactions and diminish the localization of
hsp-16.41 at the NPC during heat-shock, thus altering the expression of genes driven by this promoter.