Candida albicans is a deadly pathogen responsible for thousands of infections and deaths in the United States each year. This pathogen infects multiple host tissues by adapting to combinatorial stresses present in diverse microenvironments. C. albicans adapts to these environments through changes in gene expression. While pioneering studies have shown that changes in mRNA levels occur during the course of infection, other work in multiple organisms has shown that the translatome ? the population of mRNAs that are actively translated ? often differs greatly from the transcriptome. Little is known about the translatome employed by C. albicans during infection. Addressing this knowledge gap will have significant impacts on our understanding of fungal virulence mechanisms. The objective of this application is to survey the population of translated mRNA from C. albicans during infection of a mammalian host. This will be accomplished through two specific aims; 1. Measure the dynamic translatome of C. albicans in two mouse models of infection using RiboTags and RNA-seq; and 2. Identify novel translated regions used by C. albicans during infection of a mammalian host. In the first aim, we will use our RiboTag strain of C. albicans to isolate the translatome from infected tissues and measure it using high-throughput sequencing. We will use both public and our own computational tools to identify genes whose protein synthesis changes over the course of systemic and oropharyngeal infection. We will also compare out translatome measurements to published transcriptome data to identify candidate cis-regulatory elements important for virulence.
In aim 2, we will use Ribosome profiling from immunoprecipitated C. albicans ribosomes to identify novel translated regions. Novel peptides encoded by these regions will be tested for roles in virulence in mice. This approach is innovative in that it uses a novel approach to study the translatome in infected tissue and is expected to reveal new regulatory mechanisms used during infection. We expect the proposed research will generate new hypotheses regarding gene regulation during infection and open fresh avenues for future research into C. albicans virulence.
The proposed research is relevant to public health because identifying molecular mechanisms used by C. albicans to infect mammalian hosts is expected to ultimately improve our ability to treat fungal infections. This pathogen is a major health problem, with high infection rates in hospitals and high morbidity. As such, the proposed project is relevant to the part of the NIH mission relating to fostering innovative discoveries to improve public health.