Eric Fritz

Presented by F. Nina Papavasiliou
A.B., Harvard College
Genome-wide Characterization of the Effects of Nucleic Acid
Modifying Enzymes: Cytidine Deaminases and DNA Methylation

In biology, to show that something happens, what we call a positive result, is easy. To demonstrate with a high degree of accuracy that something does not happen, which we call a negative result, requires a type of meticulous and precise analysis that is uncommon to biologists.

Eric Fritz was trained as a chemist, and brought his meticulous and precise thinking to a very messy biological problem. This problem concerns B cells. These are the cells of the body that produce antibodies. But they don’t just produce them, they also tweak them to fit bits and pieces that are foreign to the body, and tag them for destruction. This tweaking process requires the activity of an enzyme, which normally mutates the gene fragments from which antibodies are assembled, to produce families of mutant antibodies, some of which bind the foreign particles with very high affinity.

Intuitively, it makes sense that such a mutator would need to be particularly well regulated in the cell, or else it could attack other genes and cause all sorts of problems. Many labs have contrived artificial situations to show that, indeed, human intuition must be correct, because the presence of the unregulated mutator can be very, very bad news for the cell. But is it, really? Intuition aside, Eric Fritz relied on experimental data to demonstrate that under normal conditions, the only thing the mutator does is tweak antibody genes and that, at least in B cells, it has none of the terrible other activities ascribed to it. This body of negative data, of describing what a molecule does not do, was so compelling, that it was accepted in one of the top journals without a single revision — a rare occurrence, as I’m sure most of you know. Eric’s work has set the bar high.

We’ll miss Eric, his thoughtful precision but also his dry humor, as he moves on to the next phase of his career.