  The formation of DNA loops by proteins and protein complexes is ubiquitous to
many fundamental cellular processes, including transcription, recombination,
and replication. Here we review recent advances in understanding the properties
of DNA looping in its natural context and how they propagate to the cellular
behavior through gene regulation. The results of connecting the molecular
properties with cellular physiology indicate that looping of DNA in vivo is
much more complex and easier than predicted from current models and reveals a
wealth of previously unappreciated details.
