L1-ORF1p nucleoprotein can rapidly assume distinct conformations and simultaneously bind more than one nucleic acid.

LINE-1 (L1) is a parasitic retrotransposable DNA element, active in primates for the last 80-120 Myr. L1 has generated nearly one-third of the human genome by copying its transcripts, and those of other genetic elements (e.g.

The L1-ORF1p coiled coil enables formation of a tightly compacted nucleic acid-bound complex that is associated with retrotransposition.

Long interspersed nuclear element 1 (L1) parasitized most vertebrates and constitutes ∼20% of the human genome. It encodes ORF1p and ORF2p which form an L1-ribonucleoprotein (RNP) with their encoding transcript that is copied into genomic DNA (retrotransposition). ORF1p binds single-stranded nucleic acid (ssNA) and exhibits NA chaperone activity.

Multiprotein E. coli SSB-ssDNA complex shows both stable binding and rapid dissociation due to interprotein interactions.

Escherichia coli SSB (EcSSB) is a model single-stranded DNA (ssDNA) binding protein critical in genome maintenance. EcSSB forms homotetramers that wrap ssDNA in multiple conformations to facilitate DNA replication and repair. Here we measure the binding and wrapping of many EcSSB proteins to a single long ssDNA substrate held at fixed tensions.

Characterizing Complex Nucleic Acid Interactions of LINE1 ORF1p by Single Molecule Force Spectroscopy.

The L1 retrotransposon is the dominant transposable element in mammalian genomes. L1 comprises at least 20% of the human genome. While most L1 regions are inactive, a few still retain the ability to retrotranspose.

HIV restriction factor APOBEC3G binds in multiple steps and conformations to search and deaminate single-stranded DNA.

APOBEC3G (A3G), an enzyme expressed in primates with the potential to inhibit human immunodeficiency virus type 1 (HIV-1) infectivity, is a single-stranded DNA (ssDNA) deoxycytidine deaminase with two domains, a catalytically active, weakly ssDNA binding C-terminal domain (CTD) and a catalytically inactive, strongly ssDNA binding N-terminal domain (NTD). Using optical tweezers, we measure A3G binding a single, long ssDNA substrate under various applied forces to characterize the binding interaction. A3G binds ssDNA in multiple steps and in two distinct conformations, distinguished by degree of ssDNA contraction.