Life without chromatin

Bacteria encode a collection of small, basic, abundant proteins that jointly structure the nucleoid, contribute to DNA compaction and affect the regulation of genes. These nucleoid-associated proteins (NAPs) can often be deleted without lethal effect. The common explanation for this is that individual deletions are tolerated because NAPs can act redundantly. However, a more radical scenario exists: NAPs are not required for bacterial life at all. Can cells function without chromatin? If yes, then how? To address this question, I have built an E. coli strain that carries deletions for nine major NAPs: hupA, hupB, ihfA, ihfB, hns, stpA, dps, lrp, and fis. This project will use this unique strain (∆NAP9) to determine how a bacterial cell can survive and adapt to life without chromatin, and to study the function of native and heterologous chromatin proteins when (re)introduced - alone or in combination - into this "chromatin-free" chassis. My work will open up a radically new avenue to studying bacterial chromatin and DNA-templated processes affected by a chromatinized environment, bridging the gap between in vitro and in vivo investigations of DNA transactions. I further anticipate that my work will critically inform future efforts to construct synthetic chromatin and build minimal prokaryotic cells.