This document summarizes a presentation on non-histone proteins. It defines non-histone proteins as those that remain bound to DNA after histones are removed. Non-histone proteins play important structural and regulatory roles in chromatin organization and chromosome compaction. There are hundreds of types of non-histone proteins that function in DNA replication, transcription, and chromosome segregation. Examples provided include scaffold proteins, heterochromatin protein 1, DNA polymerase, and polycomb proteins. The main roles of non-histone proteins are compacting chromatin into chromosomes and organizing chromosome structure within the nucleus.

1. Jimma University
Institute of Health Sciences
Department of Biomedical Science
Course Title: Basics of Genetics
Seminal Presentation on:- non-histone proteins
By;- Bikila Belay…RM0435/15-0
Submitted to:-Prof,Kumaresan Ramanathan
June 2023
Jimma,Ethiopa

2. CONTENTS:
• Definition of non histone proteins.
• Types of non-histone proteins.
• Non-histone Chromosomal Proteins.
• Roles of non histone in chromosomal structure.

3. Definition of non histone proteins
Is a DNA-binding nuclear protein expressed throughout the cell cycle in proliferating cells, but
not in quiescent (G0) cells.
The non-histone proteins, are a large group of heterogeneous proteins that play a role
in organization and compaction of the chromosome into higher order structures.
Non-histone proteins are those proteins in chromatin that
persist after the removal of the histones.
The chromosome is organized and compacted into higher-order
structures by a wide group of heterogeneous proteins known as
non-histone proteins.

4. Nonhistone proteins
Hundreds of other proteins that make up chromatin and are not histones
200 – molecules of each kind of no histone protein.
Large variety of functions
-Structural role – chromosome scaffold .
-Chromosome replication – e.g. DNA polymerases.
-Chromosome segregation – e.g. kinetochore proteins .

5. Cont…..
-Active in transcription –
-largest group the motor proteins of kinetochores help
during mitosis and meiosis.
-By interacting with DNA, influence when, where, and at what rate
genes give rise to their protein products.
- Non histone proteins are not a part of a nucleosome.
- Non histone proteins are not conserved across species.
- Non histone proteins are not involved in gene expression regulation.

6. Types of non-histone proteins
-Scaffold proteins,
- Heterochromatin Protein 1,
-DNA polymerase,
-Polycomb, etc. are some types of non histones and
-other motor proteins, which are essential
for cell organization.

7. Non-histone Chromosomal Proteins:
- Relatively low in abundance compared to the histones
- They include:
1) proteins for transcription (SSB DNA poly etc.
- RNA polymerases
- activators and repressors (later disc.)
(Transcription Factors)
• 2) DNA polymerase for replication.
• 3) High Mobility Group (HMG) proteins.
- moderately abundant ( average
1 HMG/nucleosome)
- role in transcription
-Structural?
- Functional?
- later disc.
• 4) Other structural proteins (Topoisomerase, etc.)

8. Non-histone Chromosomal Proteins
Structural Maintenance
of
Chromosome proteins
(SMC proteins)
Can hold two circular
DNA molecules
together
Most interesting:
SMC proteins may
reside in the
chromosome
scaffold and help
establish the radial
loops

9. Non-histone Chromosomal Proteins:
• They play vital roles in:-
-regulating processes like nucleosome remodeling,
- DNA replication,& DNA damage repair.
- RNA synthesis and processing,
- nuclear transport,/ signal transduction
- steroid hormone action and
- interphase/mitosis transition.
-autophagy and metabolism.
• The main function of non histone proteins is the compaction of chromatin in
chromosomes and organization of chromosomes inside the nucleus

10. Roles of non histone in chromosomal structure:
Non histone protein helps maintain chromosome
structure:
-The assembly of non histone proteins and the
structural integrity of vertebrate mitotic chromosomes
depend on condensin.

11. Reference:
• Woodcock, C.L.; Ghosh, R.P. Chromatin Higher-order Structure and
Dynamics. Gold Spring Harb. Perspect. Biol. 2010, a000296. [Google
Scholar] [CrossRef] [PubMed]
• Bekhor, I., Kung, G.M. & Bonner, J. (1969). Sequence-specific interaction of DNA and
chromosomal protein. J. Mol. Biol. 39, 351– 364
• Bhorjee, J.S. & Pederson, T. (1972). Nonhistone chromosomal proteins in synchronized
HeLa cells. Proc. Natl. Acad. Sci. U.S.A. 69, 3345– 3349
• Curtis Seubert. “The Difference Between Histone & Nonhistone.” Sciencing. Leaf
Group, 24 Apr. 2017. Web. 15 May 2017.